ES2888923A1 - USE OF MICROPOROUS CRYSTAL MATERIAL OF ZEOLITHIC NATURE WITH STW STRUCTURE IN HYDROCARBON ADSORPTION AND SEPARATION PROCESSES (Machine-translation by Google Translate, not legally binding) - Google Patents

Abstract

Use of microporous crystalline material of a zeolitic nature with STW structure in hydrocarbon adsorption and separation processes. The present invention describes the use of purely siliceous zeolite of the STW structure in adsorption and separation processes of hydrocarbons belonging to the gasoline range. (Machine-translation by Google Translate, not legally binding)

Description

DESCRIPTION

USE OF THE ZEOLITIC MICROPOROUS CRYSTALLINE MATERIAL WITH

STW STRUCTURE IN ADSORPTION AND SEPARATION PROCESSES

HYDROCARBONS

TECHNICAL FIELD OF THE INVENTION

The present invention belongs to the technical field of microporous crystalline materials of a zeolitic nature, useful in the production of gasoline.

STATE OF THE ART PRIOR TO THE INVENTION

Gasoline is one of the most widely used fuels and is mainly composed of hydrocarbons from the C5-C10 fractions. Its combustion efficiency is evaluated according to its octane number, or octane number, which increases with the quality of the fuel.

The hydroisomerization of short chain linear paraffins is an effective method to obtain higher octane components for gasoline blending. The feedstock for this process is a refinery stream consisting primarily of linear normal paraffins from the C5-C10 fractions. Highly active supported metal hydrogenation catalysts and hydrogen are required for the desired reactions to take place. The reaction is limited by chemical equilibrium, the use of low temperatures being preferable to minimize hydrocracking of the more reactive branched products (Pet. Sci. Technol. 2013, 31, 580-595; Energy & Fuels 2019, 33, 3828-3843 Coord Chem Rev.

2011, 255, 1558-1580). Separating multibranched products from the effluent and recycling linear and monobranched products is another way to maximize unit yield and productivity (Advanced Solutions for Paraffins Isomerization, Washington, DC, 2004; Angew. Chemie - Int. Ed. 2005, 44, 400-403).

The separation of linear from branched hydrocarbons has been known and used for years in the industry (US Patent 3070542, 1962). In most cases, this separation is carried out by means of an adsorption process, using a zeolitic adsorbent.

Zeolites are microporous crystalline aluminosilicates whose network is formed by TO4 tetrahedrons (T = Si, Al) that share vertices. The presence of aluminum in coordination tetrahedral gives rise to the negative charge in the network, which is compensated by extrareticular cationic species. Although the most usual is that the atoms in the center of the tetrahedra are Si or Al, a large number of zeotypic materials with a wide range of compositions are known, including Ti, Ge, B, P, etc. The aforementioned characteristics, with special reference to structural porosity, make zeolites very versatile materials that find application as ion exchangers, catalysts and adsorbents.

Zeolites can be structurally classified according to the opening of their channels, giving rise to extra-large, large, medium or small pore zeolites. Small-pore zeolites have channels with openings formed by 8-tetrahedral rings (8-rings, 8R), while medium-pore zeolites have 10R channels, large 12R, and finally, extra-large have channels with openings greater than 12R.

Zeolite 5A, with a small pore size, was the first to be used and is still widely used industrially for the separation of linear hydrocarbons from branched ones, although other commercial zeolites with a larger pore size have also been used, such as MFI-type zeolites (ZSM -5 and silicalite-1) and FAU-type zeolites (zeolites X and Y) (Ch. 7, Zeolites and other adsorbents, in Nanoporous Materials for Gas Storage, Springer Singapore, Singapore, 2019, pp. 173-208). Small pore zeolites are effective in separating linear hydrocarbons from mono-, di- and poly-branched hydrocarbons. However, the separation of monobranched from multibranched hydrocarbons is the ideal objective, since this separation carried out after the hydroisomerization unit would enhance the efficiency of the process, allowing a raffinate enriched in higher octane multibranched hydrocarbons to be obtained. On the other hand, the low-octane compounds, that is, the linear and monobranched hydrocarbons, would be recirculated together with the feed of the unit.

The separation of monobranched from multibranched hydrocarbons is also more technically complicated, mainly due to the fact that there are no adsorbents that effectively differentiate between both types of hydrocarbons (Recent Patents Chem. Eng.

2012, 5, 153-173). The most widely proposed materials for this purpose have low polarity, that is, they have a high Si/AI ratio and a medium pore size (10R). Silicalite-1 and zeolite ZSM-5 have been studied and patented as adsorbents and membranes for this separation, however, their selectivity towards the dibranched component over the monobranched seems to be insufficient. (US Patent 6069289 A, 2000; Phys. Chem. Chem. Phys. 2001, 3, 4390-4398; Angew. Chemie - Int. Ed. 2012, 51, 11867-11871; Sep. Purif.

Technol. 2013, 106, 56-62; Ind. Eng. Chem. Res. 1997, 36, 137-143; USPatent 6156950, 2000; Oil Gas Sci. Technol. - Rev. I'IFP 2009, 64, 759-771; US Patent 6809228 B2, 2004; US Patent 6338791 B1, 2002; AlChE J. 2002, 48, 1927-1937). Other materials with MWW, EUO, NES structures (US Patent 6809228 B2, 2004; US Patent 6784334 B2.2004; US Patent 7435865 B2, 2008; Recent Patents Chem. Eng. 2012, 5, 153-173) AFI (US Patent 5107052 , 1992), BEA, FER, FAU, ATO, AEL (US Patent 6069289 A, 2000; US Patent 3706813, 1972), MEL, MTT, MRE, (US Patent 6338791 B1, 2002) ATS and CFI (US Patent 7029572 B2 , 2006; US Patent 7037422 B2, 2006) can be found in the patent literature for this purpose, although none of them has significantly improved the behavior of MFI-type zeolites.

An additional difficulty in the separation of hydrocarbon currents is the presence of olefins in their composition, since the presence of acid centers can produce the formation of oligomers by reaction of these olefins, resulting in a strong decrease in the adsorption capacity of the adsorbent. .

Among the zeolitic structures we find the structure of the zeolite STW. It is a medium pore structure, containing 10R helical channels with openings of 5.2 * 5.7 Á (minimum and maximum opening, respectively) in one direction, perpendicularly interconnected by 8R windows of 3.0 * 4.4Á (J. Am. Chem. Soc. 2013, 135, 11975 11. The synthesis of zeolite with STW structure and high Si/AI ratio, such as HPM-1 or SSZ-110, even reaching pure silica, has been described (Korean Patent KR101636142 B1, 2016 ; US Patent 2019/0224655 A1, 2019; Angew. Chem. Int. Ed.2012, 51, 3854-3856).Materials with STW structure have been previously used in catalytic refining and separation processes of chiral alcohols both in scientific articles as in patents (Korean Patent KR101636142 B1, 2016; Proceedings of the National Academy of Sciences May 2017, 114 (20) 5101-5106; Chem. Eur. J. 2018, 24, 4121; US Patent2019/0224655 Al, 2019 ).

This invention patent describes the use of a purely siliceous zeolitic material with the STW structure, which we will call Si-STW, as an adsorbent that can act as a molecular sieve, surprisingly separating multibranched hydrocarbons through the selective adsorption of linear molecules and monobranches of a stream that contains them. The selectivity in this case is observed under both thermodynamic and kinetic control conditions, since some of the multibranched species are adsorbed on the Si-STW material in less quantity and at a lower adsorption rate than the linear and monobranched isomers. In addition, the Si-STW material outperforms silicalite-1 both in selectivity and adsorption capacity of linear or monobranched hydrocarbons. We have found that in this zeolite, in the case of the isomers of hexane, heptane and other multibranched hydrocarbons with higher carbon numbers, the relative position of the branches allows adsorption to be differentiated. The Si-STW material, being purely siliceous and not containing trivalent elements in its composition, minimizes the formation of oligomers or other products derived from reactions of adsorbed hydrocarbons on acid centers that could lead to pore blockage. Furthermore, the purely siliceous material is chemically and thermally more stable than materials of this same structure but different composition, such as germanosilicates. In this way, the material has a longer lifetime than others of a different composition.

DESCRIPTION OF THE INVENTION

The Si-STW material is a medium pore zeolite containing 10R helical channels with openings of 5.2 * 5.7 Á in one direction, perpendicularly interconnected by 8R windows of 3.0 * 4.4 Á.

The use of a microporous crystalline material of a zeolitic nature and structure STW in separation processes of hydrocarbons present in the outlet stream of a naphtha hydroisomerization unit is described here, more specifically for the separation of alkanes from the C5-C10 linear fractions and monobranched to multibranched. This zeolite also allows the separation of linear and monobranched olefins from multibranched ones.

Specifically, the present invention relates to a process for separating hydrocarbon fluids that comprises at least the following stages:

(a) contacting an inlet hydrocarbon stream, consisting of a first fluid component and a second fluid component, with an adsorbent containing the Si-STW zeolitic material, producing a non-adsorbed fluid product in which the molar ratio of the first fluid component to the second fluid component is less than the molar ratio of the first fluid component to the second fluid component in the input stream,

(b) recovery of the non-adsorbed fluid product,

(c) formation of an adsorbed fluid product whose molar ratio of first fluid component to second fluid component is greater than the molar ratio of first fluid component to second fluid component in the input stream, (d) recovery of adsorbed fluid product.

Zeolite Si-STW is characterized by its thermodynamic equilibrium adsorption capacities and adsorption rates that are considerably different for linear, monobranched and multibranched alkanes with between five and ten carbons, such as 2-methylbutane and 2,2-dimethylpropane, among others. others, which makes their separation possible. The equilibrium condition is reached when the amount of adsorbate does not increase with time at fixed conditions of adsorbate pressure and temperature. The thermodynamic efficiency or selectivity (at) of an adsorbent in separation processes is determined from the value of the quotient of the adsorption capacities of the products that are intended to be separated under equilibrium conditions. The efficiency or kinetic selectivity (ac) of an adsorbent in a separation process is determined from the value of the quotient of the diffusional time constants determined from adsorption rate experiments and the adjustment of the resulting curves by means of a model. appropriate (Ch. 6, Sorption Kinetics, in Diffusion in Nanoporous Materials (eds J. Karger, DM Ruthven and DN Theodorou), 2012, pp. 143-189).

On the other hand, the higher the adsorption capacity of a zeolite, the less adsorbent is required to remove a given volume of adsorbate. Thus, in a separation process such as the one described, it is preferred that the zeolites have high values of thermodynamic or kinetic selectivity and high adsorption capacities.

According to a particular embodiment of the present invention, step (d) for recovering the adsorbed product comprises at least (a) modifying at least the temperature or pressure of the adsorbent, (b) contacting the adsorbent containing the Si-STW zeolitic material with a third fluid component (carrying gas), of which at least a fraction is adsorbed by the adsorbent containing the Si-STW zeolitic material or (c) a combination of the above.

The hydrocarbon separation process described above is preferably carried out using swing adsorption techniques (generally known as “Swing Adsorption” techniques), putting the inlet stream in contact with an adsorbent (comprising a certain amount of zeolite Si-STW) in a swing adsorption bed, more specifically under pressure swing adsorption conditions (pressure drop generally called “Pressure Swing Adsorption”), or under temperature swing adsorption conditions ( increase of temperature, generally referred to as “Temperature Swing Adsorption”), or a combination of the above.

Preferably, multibranched compounds, especially those containing quaternary carbons, are excluded. The mixture of hydrocarbons and the Si-STW zeolite (adsorbent) is kept in contact for a certain time to ensure that the adsorption process of the linear and monobranched compounds takes place and, finally, the mixture of hydrocarbons that have not been adsorbed is removed. .

The fraction adsorbed on the zeolite is recovered by techniques such as stripping with another gas, temperature increase (temperature swing adsorption, generally referred to as “Temperature Swing Adsorption”), pressure decrease (pressure swing adsorption). , generally called "Pressure Swing Adsorption") or a combination of the above methods.

Preferably, the hydrocarbon input stream according to the present invention is composed of hydrocarbons from the C5-C10 fractions.

Although the separation conditions will depend on the composition of the hydrocarbon mixture to be separated, the process described in the present invention can be carried out at a temperature between 0 and 200oC, preferably between 0 and 100oC, more preferably between 0oC. and 60oC and at a hydrocarbon partial pressure between 0.0001 and 10 bar, preferably between 0.0001 and 5 bar, more preferably between 0.0001 and 1 bar.

As previously mentioned, the composition of the hydrocarbon mixture is important for the process.

According to a particular embodiment, the first fluid component comprises paraffins and olefins that can be linear, monobranched, multibranched, or combinations thereof.

According to another particular embodiment, the first fluid component comprises monobranched, multibranched paraffins and paraffins or combinations of the above, the branches present being methyl groups.

According to another particular embodiment, the first fluid component comprises linear paraffins, monobranched, multibranched or combinations of the above.

According to another particular embodiment, the first fluid component comprises monobranched, multibranched paraffins or combinations of the above, the branches present being methyl groups.

According to another particular embodiment, the first fluid component comprises linear, monobranched, multibranched olefins or combinations of the above.

According to another particular embodiment, the first fluid component comprises monobranched, multibranched or combinations of the above, the branches present being methyl groups.

According to another particular embodiment, in the hydrocarbon separation process described above, the multibranched hydrocarbons of the first fluid component preferably have 3 or fewer branches.

According to another particular embodiment, the multibranched hydrocarbons of the first fluid component do not have quaternary carbons.

According to another particular embodiment, the multibranched hydrocarbons of the first component have branches that are at chain distances greater than 2 carbons.

According to the process of the present invention, the second fluid component comprises paraffins and olefins that can be monobranched, multibranched or combinations of the above.

According to a particular embodiment, the second fluid component comprises monobranched paraffins and paraffins, the branches being groups that include more than one carbon, such as, for example, ethyl, 1-propyl or 2-propyl.

According to another particular embodiment, the second fluid component comprises multibranched paraffins and paraffins, at least one of the branches being a group that includes more than one carbon.

According to another particular embodiment, the second fluid component comprises multibranched paraffins and paraffins having at least one quaternary carbon.

According to another particular embodiment, the second fluid component comprises paraffins and multibranched olefins whose branches are at chain distances less than (n-5), where n is the total number of carbons in the molecule.

According to another particular embodiment, the second fluid component comprises monobranched, multibranched paraffins or combinations of the above.

According to another particular embodiment, the second fluid component comprises monobranched paraffins, the branches being groups that include more than one carbon.

According to another particular embodiment, the second fluid component comprises multibranched paraffins, at least one of the branches being a group that includes more than one carbon.

According to another particular embodiment, the second fluid component comprises multibranched paraffins having at least one quaternary carbon.

According to another particular embodiment, the second fluid component comprises multibranched paraffins whose branches are at chain distances less than (n-5), where n is the total number of carbons in the molecule.

According to another particular embodiment, the second fluid component comprises monobranched, multibranched olefins or combinations of the above.

According to another particular embodiment, the second fluid component comprises monobranched chains, the branches being groups that include more than one carbon

According to another particular embodiment, the second fluid component comprises multibranched chains, at least one of the branches being a group that includes more than one carbon.

According to another particular embodiment, the second fluid component comprises multibranched defines having at least one quaternary carbon.

According to another particular embodiment, the second fluid component comprises multibranched olefins whose branches are at chain distances less than (n-5), where n is the total number of carbons in the molecule.

According to the hydrocarbon separation process described above, the inlet stream is contacted with the adsorbent containing the Si-STW zeolitic material under the appropriate conditions to carry out a separation of the first fluid component under kinetic control, or in the which the inlet stream is brought into contact with the adsorbent containing the Si-STW zeolitic material under suitable conditions to carry out a separation of the first fluid component under thermodynamic control, or a combination of the above.

According to a particular embodiment, n-pentane is preferentially adsorbed and 2,2-dimethylpropane is not preferentially adsorbed.

According to another particular embodiment, 2-methylbutane is preferentially adsorbed and 2,2-dimethylpropane is not preferentially adsorbed.

According to another particular embodiment, n-hexane is preferentially adsorbed and 2,2-dimethylbutane is not preferentially adsorbed.

According to another particular embodiment, 2-methylpentane is preferentially adsorbed and 2,2-dimethylbutane is not preferentially adsorbed.

According to another particular embodiment, 3-methylpentane is preferentially adsorbed and 2,2-dimethylbutane is not preferentially adsorbed.

According to another particular embodiment, 2,3-dimethylbutane is preferentially adsorbed and 2,2-dimethylbutane is not preferentially adsorbed.

According to another particular embodiment, 1-hexene is preferentially adsorbed and 3,3-dimethyl-1-butene is not preferentially adsorbed.

According to another particular embodiment, 4-methyl-1-pentene is preferentially adsorbed and 3,3-dimethyl-1-butene is not preferentially adsorbed.

According to another particular embodiment, n-heptane is preferentially adsorbed and 2,2-dimethylpentane is not preferentially adsorbed.

According to another particular embodiment, n-heptane is preferentially adsorbed and 2,3-dimethylpentane is not preferentially adsorbed.

According to another particular embodiment, n-heptane is preferentially adsorbed and 3,3-dimethylpentane is not preferentially adsorbed.

According to another particular embodiment, 2-methylhexane is preferentially adsorbed and 2,2-dimethylpentane is not preferentially adsorbed.

According to another particular embodiment, 2-methylhexane is preferentially adsorbed and 2,3-dimethylpentane is not preferentially adsorbed.

According to another particular embodiment, 2-methylhexane is preferentially adsorbed and 3,3-dimethylpentane is not preferentially adsorbed.

According to another particular embodiment, 3-methylhexane is preferentially adsorbed and 2,2-dimethylpentane is not preferentially adsorbed.

According to another particular embodiment, 3-methylhexane is preferentially adsorbed and 2,3-dimethylpentane is not preferentially adsorbed.

According to another particular embodiment, 3-methylhexane is preferentially adsorbed and 3,3-dimethylpentane is not preferentially adsorbed.

According to another particular embodiment, 2,4-dimethylpentane is preferentially adsorbed and 2,2-dimethylpentane is not preferentially adsorbed.

According to another particular embodiment, 2,4-dimethylpentane is preferentially adsorbed and 2,3-dimethylpentane is not preferentially adsorbed.

According to another particular embodiment, 2,4-dimethylpentane is preferentially adsorbed and 3,3-dimethylpentane is not preferentially adsorbed.

According to another particular embodiment, 2,3-dimethylpentane is preferentially adsorbed and 2,2-dimethylpentane is not preferentially adsorbed.

According to another particular embodiment, 2,3-dimethylpentane is preferentially adsorbed and 3,3-dimethylpentane is not preferentially adsorbed.

According to another particular embodiment, 1-heptene is preferentially adsorbed and 4,4-dimethyl-1-pentene is not preferentially adsorbed.

According to another particular embodiment, 2,3-dimethylbutane is preferentially adsorbed and 2,3-dimethylpentane is not preferentially adsorbed.

According to a particular embodiment, n-pentane is adsorbed faster than 2,2-dimethylpropane at low pressure.

According to another particular embodiment, 2-methylbutane is adsorbed faster than 2,2-dimethylpropane at pressures below 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, n-hexane is adsorbed faster than 2,2-dimethylbutane at pressures below 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 2-methylpentane is adsorbed faster than 2,2-dimethylbutane at pressures below 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 3-methylpentane is adsorbed faster than 2,2-dimethylbutane at pressures below 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 2,3-dimethylbutane is adsorbed faster than 2,2-dimethylbutane at pressures below 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 1-hexene is adsorbed faster than 3,3-dimethyl-1-butene at pressures below 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 4-methyl-1-pentene is adsorbed faster than 3,3-dimethyl-1-butene at pressures below 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, n-heptane is adsorbed faster than 2,2-dimethylpentane at pressures below 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, n-heptane is adsorbed faster than 2,3-dimethylpentane at pressures below 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, n-heptane is adsorbed faster than 3,3-dimethylpentane at pressures below 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 2-methylhexane is adsorbed faster than 2,2-dimethylpentane at pressures below 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 2-methylhexane is adsorbed faster than 2,3-dimethylpentane at pressures below 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 2-methylhexane is adsorbed faster than 3,3-dimethylpentane at pressures below 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 3-methylhexane is adsorbed faster than 2,2-dimethylpentane at pressures below 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 3-methylhexane is adsorbed faster than 2,3-dimethylpentane at pressures below 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 3-methylhexane is adsorbed faster than 3,3-dimethylpentane at pressures below 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 2,4-dimethylpentane is adsorbed faster than 2.2-dimethylpentane at pressures below 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 2,4-dimethylpentane is adsorbed faster than 2,3-dimethylpentane at pressures below 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 2,4-dimethylpentane is adsorbed faster than 3,3-dimethylpentane at pressures below 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 2,3-dimethylpentane is adsorbed faster than 2.2-dimethylpentane at pressures below 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 2,3-dimethylpentane is adsorbed faster than 3,3-dimethylpentane at pressures below 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 1-heptene is adsorbed faster than 4,4-dimethyl-1-pentene at pressures below 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 2,3-dimethylbutane is adsorbed faster than 2,3-dimethylpentane at pressures below 50% of the pressure necessary to reach the maximum adsorption capacity.

According to a particular embodiment, n-pentane is adsorbed faster than 2,2-dimethylpropane at pressures above 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 2-methylbutane is adsorbed faster than 2,2-dimethylpropane at pressures above 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, n-hexane is adsorbed faster than 2,2-dimethylbutane at pressures above 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 2-methylpentane is adsorbed faster than 2,2-dimethylbutane at pressures above 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 3-methylpentane is adsorbed faster than 2,2-dimethylbutane at pressures above 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 2,3-dimethylbutane is adsorbed faster than 2,2-dimethylbutane at pressures above 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 1-hexene is adsorbed faster than 3,3-dimethyl-1-butene at pressures above 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 4-methyl-1-pentene is adsorbed faster than 3,3-dimethyl-1-butene at pressures above 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, n-heptane is adsorbed faster than 2,2-dimethylpentane at pressures above 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, n-heptane is adsorbed faster than 2,3-dimethylpentane at pressures above 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, n-heptane is adsorbed faster than 3,3-dimethylpentane at pressures above 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 2-methylhexane is adsorbed faster than 2,2-dimethylpentane at pressures above 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 2-methylhexane is adsorbed faster than 2,3-dimethylpentane at pressures above 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 2-methylhexane is adsorbed faster than 3,3-dimethylpentane at pressures above 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 3-methylhexane is adsorbed faster than 2,2-dimethylpentane at pressures above 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 3-methylhexane is adsorbed faster than 2,3-dimethylpentane at pressures above 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 3-methylhexane is adsorbed faster than 3,3-dimethylpentane at pressures above 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 2,4-dimethylpentane is adsorbed faster than 2,2-dimethylpentane at pressures above 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 2,4-dimethylpentane is adsorbed faster than 2,3-dimethylpentane at pressures above 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 2,4-dimethylpentane is adsorbed faster than 3,3-dimethylpentane at pressures above 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 2,3-dimethylpentane is adsorbed faster than 2.2-dimethylpentane at pressures above 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 2,3-dimethylpentane is adsorbed faster than 3,3-dimethylpentane at pressures above 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 1-heptene is adsorbed faster than 4,4-dimethyl-1-pentene at pressures above 50% of the pressure necessary to reach the maximum adsorption capacity.

According to another particular embodiment, 2,3-dimethylbutane is adsorbed faster than 2,3-dimethylpentane at pressures above 50% of the pressure necessary to reach the maximum adsorption capacity.

In the present invention, it is shown that the Si-STW zeolite exhibits considerably different adsorption capacities and speeds for hydrocarbons in the gasoline range, depending on the number and relative position of its branches. The kinetic and thermodynamic selectivities favor the adsorption of linear and monobranched compounds over multibranched ones. Within the multibranched compounds, the adsorption preference decreases the closer the substituents are to each other, being the compounds that present quaternary carbons the most disadvantaged thermodynamically and kinetically. Therefore, the Si-STW zeolite is a very suitable adsorbent to carry out hydrocarbon separation processes at the outlet of a hydroisomerization unit.

As previously mentioned, the separation process of this invention comprises the use of swing adsorption techniques (generally known as "Swing Adsorption" techniques). This implies that a certain amount of Si-STW zeolite is put in contact with a mixture of hydrocarbons, preferably in the C5-C10 fractions, and multibranched compounds, especially those with quaternary carbons, are excluded. The mixture of hydrocarbons and the Si-STW zeolite is kept in contact for a certain time to guarantee that the adsorption process of the linear and monobranched compounds takes place and, finally, the mixture of hydrocarbons that have not been adsorbed is removed. The fraction adsorbed on the zeolite is recovered by techniques such as stripping with another gas, temperature increase (temperature swing adsorption, generally referred to as “Temperature Swing Adsorption”), pressure decrease (pressure swing adsorption). , generally called "Pressure Swing Adsorption") or a combination of the above methods.

This separation process can also be carried out in columns, in which case different hydrocarbon fronts are obtained depending on whether they are more or less strongly retained and also depending on their adsorption speed on the Si-STW zeolite bed.

Throughout the description and claims the word "comprises" and its variants (consists of, entails) are not intended to exclude other technical characteristics, additives, components or steps. Other objects, advantages and features of the invention will be apparent to those skilled in the art in part from the description and in part from the practice of the invention. The following examples are provided by way of illustration, and are not intended to be limiting of the present invention.

Brief description of the figures:

Figure 1: Adsorption isotherms of compounds of the C5 fraction in Si-STW.

Figure 2: Adsorption isotherms of compounds of the C6 fraction in Si-STW

Figure 3: Adsorption isotherms of compounds of the C7 fraction in Si-STW

Figure 4: Adsorption kinetics at 25 °C and 1 mbar.

Figure 5: Adsorption kinetics at 250C and 300, 150 or 50 mbar, depending on whether the compound belongs to the C5, C6 or C7 fractions, respectively.

EXAMPLES

Example 1. Preparation of the structure directing agent (ADE) for the subsequent synthesis of the Si-STW material.

1,2-Dimethylimidazole (16.64 g, 0.168 mol) was dissolved in ethanol (50 mL) and 1,4-dibromobutane (8.00 mL, 0.067 mol) was added. The mixture was kept under stirring at 700C for 72 h. The product was filtered off, washed with ether and dried in vacuo (26.47 g, 97%). The ADE bromide salt was finally converted to the hydroxide form by ion exchange with Amberlite-IRN-78 (OH) and the corresponding hydroxide concentration was determined by titration using phenolphthalein as a pH indicator.

Example 2. Preparation of the Si-STW material.

The Si-STW material was hydrothermally synthesized. Specifically, tetraethylorthosilicate (4.17 g, 20 mmol), ADE(OH)2 hydroxide solution (42.00 g, 3.36 wt%, 5 mmol) and hydrofluoric acid (50 wt%, 10 mmol) were mixed and the mixture was homogenized. to form a gel with the following molar composition:

Si02 : 0.25 ADE(OH)2 : 0.5 HF : 4 H20

The mixture was distributed in Teflon tubes that were placed in stainless steel autoclaves and heated at 1750C for 7 days with rotation (60 rpm). After this time, the autoclaves were cooled down and the solid was filtered, washed with deionized water and dried at 1000C. The zeolite was subjected to calcination in air at 550°C for five hours in order to remove the occluded organic.

Example 3. Adsorption of n-pentane at 300 mbar on the Si-STW material at 250C.

The measurement of the adsorption capacity of n-pentane in the Si-STW material, prepared according to Example 2 at 25°C and 300 mbar corresponds to 2.17 mmol/g. Likewise, the value obtained after carrying out 50 adsorption/desorption cycles with this and other compounds remains the same, which shows that the Si-STW material retains its adsorption capacity. The diffusional time constant calculated from an adsorption kinetic experiment is of the order of 3-10'3 s-1.

Example 4. Adsorption of 2-methylbutane at 300 mbar on the Si-STW material at 25°C.

The measurement of the pentane adsorption capacity in the Si-STW material, prepared according to Example 2 at 250C and 300 mbar corresponds to 1.70 mmol/g. The diffusional time constant calculated from an adsorption kinetic experiment is of the order of 2-10.3 s_1.

Example 5. Adsorption of 2,2-dimethylpropane at 300 mbar on the Si-STW material at 25°C.

The measurement of the adsorption capacity of 2,2-dimethylpropane in the Si-STW material, prepared according to Example 2 at 25°C and 300 mbar corresponds to 1.22 mmol/g. The diffusional time constant calculated from an adsorption kinetic experiment is of the order of 2-10-5 s-1.

Example 6. Adsorption of n-hexane at 150 mbar on the Si-STW material at 25°C.

The measurement of the adsorption capacity of n-hexane in the Si-STW material, prepared according to Example 2 at 25°C and 150 mbar corresponds to 1.77 mmol/g. The diffusional time constant calculated from an adsorption kinetic experiment is of the order of 2-10.3 s_1.

Example 7. Adsorption of 2-methylpentane at 150 mbar on the Si-STW material at 25°C.

The measurement of the adsorption capacity of 2-methylpentane in the Si-STW material, prepared according to Example 2 at 25°C and 150 mbar corresponds to 1.66 mmol/g. The diffusional time constant calculated from an adsorption kinetic experiment is of the order of 2-10'3 s-1

Example 8. Adsorption of 2,2-dimethylbutane at 300 mbar on the Si-STW material at 25°C.

The measurement of the adsorption capacity of 2,2-dimethylbutane in the Si-STW material, prepared according to Example 2 at 25°C and 150 mbar corresponds to 1.00 mmol/g. The diffusional time constant calculated from an adsorption kinetic experiment is of the order of 3-10-6 s-1.

Example 9. Adsorption of 2,3-dimethylbutane at 150 mbar on the Si-STW material at 25°C.

The measurement of the adsorption capacity of 2,3-dimethylbutane in the Si-STW material, prepared according to Example 2 at 25°C and 150 mbar corresponds to 1.64 mmol/g. The diffusional time constant calculated from an adsorption kinetic experiment is of the order of T10'5 S'1.

Example 10. Adsorption of 1-hexene at 150 mbar on the Si-STW material at 25°C.

The measurement of the adsorption capacity of 1-hexene in the Si-STW material, prepared according to Example 2 at 250C and 150 mbar corresponds to 1.80 mmol/g. The diffusional time constant calculated from an adsorption kinetic experiment is of the order of 2-10.3 s_1.

Example 11. Adsorption of 4-methyl-1-pentene at 150 mbar in the Si-STW material at 250C.

The measurement of the adsorption capacity of 4-methyl-1-pentene in the Si-STW material, prepared according to Example 2 at 25°C and 150 mbar corresponds to 1.67 mmol/g. The diffusional time constant calculated from an adsorption kinetic experiment is of the order of 2-10-3 s-1.

Example12. Adsorption of 3,3-dimethyl-1-butene at 150 mbar on the Si-STW material at 250C.

The measurement of the adsorption capacity of 3,3-dimethyl-1-butene in the Si-STW material, prepared according to Example 2 at 25°C and 150 mbar, is greater than 1.0 mmol/g, but the slowness of the adsorption process adsorption makes it impossible to determine the maximum capacity accurately. The diffusional time constant calculated from an adsorption kinetic experiment is of the order of 5-10-6 s-1.

Example 13. Adsorption of n-heptane at 50 mbar on the Si-STW material at 25°C.

The measurement of the adsorption capacity of n-heptane in the Si-STW material, prepared according to Example 2 at 25°C and 50 mbar corresponds to 1.70 mmol/g. The diffusional time constant calculated from an adsorption kinetic experiment is of the order of 2-10.3 s-1.

Example 14. Adsorption of 3-methylhexane at 50 mbar on the Si-STW material at 25°C. The measurement of the adsorption capacity of 3-methylhexane in the Si-STW material, prepared according to Example 2 at 25°C and 50 mbar corresponds to 1.64 mmol/g. The diffusional time constant calculated from an adsorption kinetic experiment is of the order of 2-10.3 s-1.

Example 15. Adsorption of 2,3-dimethylpentane at 50 mbar on the Si-STW material at 25°C.

The measurement of the adsorption capacity of 2,3-dimethylpentane in the Si-STW material, prepared according to Example 2 at 25°C and 50 mbar, is greater than 1.0 mmol/g, but the slowness of the adsorption process prevents determining the adsorption capacity. exact maximum capacity. The diffusional time constant calculated from an adsorption kinetic experiment is less than 5 -10-6 s-1.

Example 16. Adsorption of 2,4-dimethylpentane at 50 mbar on the Si-STW material at 25°C.

The measurement of the adsorption capacity of 2,4-dimethylpentane in the Si-STW material, prepared according to Example 2 at 25°C and 50 mbar, is greater than 1.60 mmol/g, but the slowness of the adsorption process prevents determining the adsorption capacity. exact maximum capacity. The diffusional time constant calculated from an adsorption kinetic experiment is less than 2-10-3s-1.

Example 17. Adsorption of 1-heptene at 50 mbar on the Si-STW material at 250C.

The measurement of the adsorption capacity of 1-heptene in the Si-STW material, prepared according to Example 2 at 25°C and 50 mbar corresponds to 1.73 mmol/g. The diffusional time constant calculated from an adsorption kinetic experiment is of the order of 2-10.3 s_1.

Example18. Adsorption of 4,4-dimethyl-1-pentene at 50 mbar on the Si-STW material at 250C.

The measurement of the adsorption capacity of 4,4-dimethyl-1-pentene in the Si-STW material, prepared according to Example 2 at 25°C and 50 mbar, is greater than 0.9 mmol/g, but the slowness of the adsorption process adsorption makes it impossible to determine the maximum capacity accurately. The diffusional time constant calculated from an adsorption kinetic experiment is less than 3 -10-6 s-1.

Claims (34)

1. Hydrocarbon fluid separation process characterized in that it comprises at least the following stages: (a) contacting an inlet hydrocarbon stream, consisting of a first fluid component and a second fluid component, with an adsorbent containing the Si-STW zeolitic material, producing a non-adsorbed fluid product in which the molar ratio of the first fluid component to the second fluid component is less than the molar ratio of the first fluid component to the second fluid component in the input stream, (b) recovery of the non-adsorbed fluid product, (c) formation of an adsorbed fluid product whose molar ratio of first fluid component to second fluid component is greater than the molar ratio of first fluid component to second fluid component in the input stream, (d) recovery of adsorbed fluid product. 2. Hydrocarbon separation process according to claim 1, characterized in that step (d) of recovering the adsorbed product comprises, at least, (a) the modification of at least the temperature or pressure of the adsorbent, (b) putting into contacting the Si-STW zeolitic material-containing adsorbent with a third fluid component, of which at least a fraction is adsorbed by the Si-STW zeolitic material-containing adsorbent or (c) a combination of the foregoing. 3. Hydrocarbon separation process according to one of the preceding claims, characterized in that it comprises contacting the inlet stream with an adsorbent in a swing adsorption bed. 4. Hydrocarbon separation process according to claim 3, characterized in that the swing adsorption bed conditions are selected from pressure swing adsorption conditions, temperature swing adsorption conditions, or a combination of the above . 5. Hydrocarbon separation process according to one of the preceding claims, characterized in that the inlet stream is composed of hydrocarbons of the C5-C10 fractions. 6. Hydrocarbon separation process according to one of the preceding claims, characterized in that the inlet stream is brought into contact with the adsorbent containing the Si-STW zeolitic material at a hydrocarbon partial pressure of 0.0001 to 10 bar. 7. Hydrocarbon separation process according to claim 6, characterized in that the partial pressure of hydrocarbons is between 0.0001 and 5 bar. 8. Hydrocarbon separation process according to one of the preceding claims, characterized in that the inlet stream is exposed to the adsorbent at temperatures between 0 and 2000C. 9. Hydrocarbon separation process according to claim 8, characterized in that the temperature is between 0 and 1000C. Hydrocarbon separation process according to one of the claims, characterized in that the first fluid component comprises paraffins and olefins that can be linear, monobranched, multibranched or combinations thereof. 11. Hydrocarbon separation process according to claim 10, characterized in that the first fluid component comprises paraffins and monobranched, multibranched paraffins or combinations of the above, the branches present being methyl groups. 12. Hydrocarbon separation process according to claim 10, characterized in that the first fluid component comprises linear, monobranched, multibranched paraffins or combinations of the above. 13. Hydrocarbon separation process according to claim 12, characterized in that the first fluid component comprises monobranched, multibranched paraffins or combinations of the above, the branches present being methyl groups. 14. Hydrocarbon separation process according to claim 10, characterized in that the first fluid component comprises linear, monobranched, multibranched olefins or combinations of the above. 15. Hydrocarbon separation process according to claim 14, characterized in that the first fluid component comprises monobranched, multibranched olefins or combinations of the above, the branches present being methyl groups. Hydrocarbon separation process according to one of the preceding claims, characterized in that the multibranched hydrocarbons of the first fluid component have 3 or fewer branches. Hydrocarbon separation process according to one of the preceding claims, characterized in that the multibranched hydrocarbons of the first fluid component do not have quaternary carbons. 18. Hydrocarbon separation process according to one of the preceding claims, characterized in that the multibranched hydrocarbons of the first component have branches that are at chain distances greater than 2 carbons. 19. Hydrocarbon separation process according to one of the preceding claims, characterized in that the second fluid component comprises paraffins and olefins that can be monobranched, multibranched or combinations of the above. 20. Hydrocarbon separation process according to claim 19, characterized in that the second fluid component comprises monobranched paraffins and paraffins, the branches being groups that include more than one carbon. 21. Hydrocarbon separation process according to one of claims 19 and 20, characterized in that the second fluid component comprises paraffins and multibranched paraffins, at least one of the branches being a group that includes more than one carbon. 22. Hydrocarbon separation process according to one of claims 19 to 21, characterized in that the second fluid component comprises paraffins and multibranched paraffins having at least one quaternary carbon. 23. Hydrocarbon separation process according to one of claims 19 to 22, characterized in that the second fluid component comprises paraffins and multibranched paraffins whose branches are at chain distances less than (n - 5) being n the total number of carbons in the molecule. 24. Hydrocarbon separation process according to claim 19, characterized in that the second fluid component comprises monobranched, multibranched paraffins or combinations of the above. 25. Hydrocarbon separation process according to claim 24, characterized in that the second fluid component comprises monobranched paraffins, the branches being groups that include more than one carbon. 26. Hydrocarbon separation process according to one of claims 24 and 25, characterized in that the second fluid component comprises multibranched paraffins, at least one of the branches being a group that includes more than one carbon. 27. Hydrocarbon separation process according to one of claims 24 to 26, in which the second fluid component comprises multibranched paraffins having at least one quaternary carbon. 28. Hydrocarbon separation process according to one of claims 24 to 27, characterized in that the second fluid component comprises multibranched paraffins whose branches are at chain distances less than (n - 5), where n is the total number of carbons in the molecule. 29. Hydrocarbon separation process according to claim 19, characterized in that the second fluid component comprises monobranched, multibranched olefins or combinations of the above. 30. Hydrocarbon separation process according to claim 29, in which the second fluid component comprises monobranched defines, the branches being groups that include more than one carbon 31. Process for separating hydrocarbons according to one of claims 29 and 30, characterized in that the second fluid component comprises multibranched chains, at least one of the branches being a group that includes more than one carbon. 32. Hydrocarbon separation process according to one of claims 29 and 31, wherein the second fluid component comprises multibranched olefins having at least one quaternary carbon. 33. Hydrocarbon separation process according to one of claims 29 and 32, characterized in that the second fluid component comprises multibranched chains whose branches are at chain distances less than (n - 5), where n is the total number of carbons in the molecule. 34. Hydrocarbon separation process according to any one of the preceding claims, characterized in that the inlet stream is put in contact with the adsorbent containing the Si-STW zeolitic material under the appropriate conditions to carry out a separation of the first fluid component under kinetic control, or in which the inlet stream is brought into contact with the adsorbent containing the Si-STW zeolitic material under suitable conditions to carry out a separation of the first fluid component under thermodynamic control, or a combination of the previous.