JPS6051785A - Method for liquefying brown coal by two-stage hydrogenation - Google Patents

Abstract

PURPOSE:To allow secondary hydrogenation to proceed efficiently by removing efficiently pre-asphaltene component, by using a specified naphtha fraction as a deashing solvent in a solvent-refined coal deashing stage after the primary hydrogenation in a two-stage hydrogenation method for brown coal. CONSTITUTION:Brown coal is mixed with a solvent, the resulting slurry is subjected to a primary hydrogenation in the presence of an iron catalyst at a high temp. under a high pressure, and distillation (1) is carried out. In the distillation (1), the solvent-refined coal is recovered by recovering an equilibrium solvent, and naphtha can be obtd. as a product. Since ash is still contained in the solvent-refined coal obtd. by the distillation (1), a deashing treatment is carried out. In the deashing stage, naphtha having a delta value of 7.4-8.5 is used as a deashing solvent and pre-asphaltene component in the solvent-refined coal is also removed together with ash. Though naphtha obtd. by distillation (3) after the secondary hydrogenation can be used as the deashing solvent naphtha, the secondary naptha having a required delta value or a separately prepared org. solvent is used in the prerunning stage and after the operation is brought into a regular running state, the secondary naphtha is supplied only in a quantity which supplements distillation shortage.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a two-stage hydrogenation and liquefaction method for lignite, and in particular, in the deashing process of solvent refined coal (SRC) after the primary hydrogenation, pre-asphaltene components are efficiently removed together with ash, and the secondary The present invention relates to a two-stage hydrogenation and liquefaction method that allows hydrogenation to proceed efficiently.

Due to recent resource and energy issues, technology to liquefy coal, which has abundant reserves, has been attracting attention as a technology to obtain liquid fuel to replace oil.In particular, technology to liquefy lignite, which accounts for the majority of coal reserves, is rapidly progressing. It is being One of the most representative methods is the hydrogenation-liquefaction method, in which lignite is mixed with a solvent and a catalyst and hydrogenated at high temperature and pressure in the presence of hydrogen to obtain SRC and liquefied oil.
By the way, in order to obtain liquefied oil in high yield by the hydrogenation liquefaction method, it is possible to increase the hydrogen decomposition from SRC to liquefied oil by making the reaction conditions harsher. The oil is further decomposed and gasified, and the yield of liquefied oil is rather reduced. As a solution to these problems, a two-stage hydrogenation and liquefaction method has been proposed in which the hydrogenated product is distilled to recover the liquefied distillate oil, and then the remaining SRC is rehydrogenated, and has achieved certain results. In other words, the two-stage hydrogenation and liquefaction method involves mixing lignite powder with a suitable solvent, adding an Fe-based catalyst to the mixture, performing primary hydrogenation at high temperature and pressure in the presence of hydrogen, and distilling the product. Separation into liquefied oil and residual oil (including ash and catalyst). After deashing the residual oil to obtain SRC, a catalyst such as M□, W, or CoXNi, which has higher hydrogenation activity than Fe-based catalysts, is added to it for secondary hydrogenation, and The SRC that could not be completely liquefied by addition is further decomposed to recover liquefied oil. As is well known, the above-mentioned deashing treatment is carried out to prevent a decrease in the activity of the secondary hydrogenation catalyst due to ash content, but according to what the present inventors have confirmed through experiments, the secondary water It was confirmed that the catalytic activity of the added catalyst was significantly reduced not only by the ash content but also by the pre-asphaltene component in the SRC.

Based on this confirmation result, we established a method for performing secondary hydrogenation after first removing pre-asphaltenes from the SRC obtained by primary hydrogenation, and filed a patent application (fr&p.
-284541).

The present invention was carried out as a part of research to improve the efficiency of secondary hydrogenation and liquefaction in such a two-stage hydrogenation and liquefaction method. By doing so, the pre-asphaltene component, which is the main cause of catalyst deactivation, is removed together with the ash content, thereby increasing the hydrogenation and liquefaction efficiency. That is, the structure of the two-stage hydrogenation and liquefaction method according to the present invention is to add and mix a liquefaction solvent and a hydrogenation catalyst to lignite, and perform quaternary hydrogenation at high temperature and high pressure in the presence of hydrogen. In a two-stage hydrogenation and liquefaction method for lignite, in which SRC, which is a product, is deashed and then subjected to secondary hydrogenation in a fixed bed hydrogenation catalyst bed, in the deashing step, one of the secondary hydrogenation products is used as a deashing solvent. Using a naphtha fraction having a solubility parameter (δ) of 7.4 to 8.5 at 25°C,
The gist of this method is to increase the secondary hydrogenation efficiency by removing pre-asphaltene components in SRC together with deashing.

In the present invention, the pre-asphaltene component is, for example, “
It is defined as a substance that is soluble in pyridine, quinoline, or tetrahydrofuran and insoluble in benzene or toluene, as shown in "Catalyst Vol. 22, pages 60 and 71," and this is the secondary hydrogenation raw material. If a large amount is contained in the SRC, the secondary hydrogenation catalyst will be deactivated in a short time as described above, making it impossible to increase the recovery rate of liquefied oil. However, as detailed below, the solubility parameter (δ) is used as a solvent for deashing.
When an organic solvent having a ratio of 7.4 to 8.5 is used, the pre-asphaltene component is removed as an insoluble material in the deashing step, and a decrease in the activity of the secondary hydrogenation catalyst is prevented as much as possible.

By the way, as mentioned above, from the sole purpose of removing the pre-asphaltene component in the primary hydrogenation product, it is sufficient to select and use an organic solvent with a low solubility parameter (δ). If it is too low, a considerable amount of the benzene soluble components (BS) and hexane soluble components (H8) in the SRC that are to be supplied as secondary hydrogenation raw materials will be removed as insolubles, making it difficult to recover the liquefied oil. The amount will be significantly reduced. Therefore, in order to effectively utilize the above idea industrially, it is necessary to use the deashing solvent as much as possible without dissolving the ash and pre-asphaltenes in the primary hydrogenation product, and as much as possible of the BS and HS components. It is necessary to select a solvent that can suppress the loss of the secondary hydrogenation raw material as much as possible.

Therefore, the present inventors investigated the solubility parameters of various organic solvents for SRC with a typical component composition obtained by primary hydrogenation [however, ash was removed in advance and only organic matter was left: pyridine soluble component (PS)]. (value at 2225°C) and the solubility of the above SRC component was investigated. S used
An example of the component ratio based on the solubility of RC in pyridine, benzene, and hexane is shown in Table 1 below. In the experiment, SRC was dispersed in a solvent four times the amount (weight ratio) of the SRC, and the critical temperature of the solvent was -30°.
The mixture was filtered at a temperature of C to collect soluble and insoluble components.

Table 1 Component ratio of SRC PS: Pyridine soluble component B■: Benzene insoluble component BS: Benzene soluble component I■l: Hexane insoluble component H8: Hexane soluble component The results are as shown in Figure 1. As the solubility parameter (δ) of the solvent increases, the amount of solvent-soluble matter in the SRC increases. That is, when a solvent with (δ) of 7.8 is used, the soluble content is only 80%, but when a solvent with (δ) of 9.0 is used, 9596 of the SRC is dissolved. Here, it can be seen that the (δ) of the solvent in which the BI component corresponding to the pre-asphaltene component of 5RC (PS) is insoluble and is suitable as a secondary hydrogenation raw material and the S component is soluble is 8.2. However, as is well known, SRC is a complex mixture of many types of hydrogen cracked products, and it is not possible to completely separate the BI and BS components, and even the BI component contains a small amount of BS. Even if it is a BS component, a small amount of BI component will also be mixed in. However, the component ratio of SRC itself varies depending on the type of lignite used as the starting material, primary hydrogenation conditions, etc. The range of fluctuation in the SRC component ratio is considered to be about 25% above and below the average component ratio shown in Table 1. Therefore, when this fluctuation range is applied to FIG. 1 to determine the preferred range of the solubility parameter (δ), the range (δ) is −7.4 to 8.5, as shown by the broken line in FIG. Incidentally, if (δ) is less than 7.4, a large amount of BS and HI will be removed as insoluble components along with BI in the demineralization process, resulting in a large loss as a raw material for secondary hydrogenation, resulting in a loss of liquefied oil. Collection amount decreases. On the other hand, if (δ) exceeds 8.5, the equivalent amount of BI in the SRC will be mixed into the SRC for secondary hydrogenation, making it impossible to effectively prevent the deactivation of the secondary hydrogenation catalyst. As is clear from the above, the solubility parameter (δ) of the deashing solvent is set to the optimum value (δ) according to the component ratio of SRC obtained by primary hydrogenation from the above-mentioned preferred range.
δ) is best selected, and the most common is SRC with an average component ratio as shown in Table 1 (and Figure 1) above.
A solvent (e.g. cyclohexane) with a solubility parameter of about 8.2, which corresponds to an optimal (δ) value of 8.2. Although it is of course possible to use a general industrial organic solvent as the deashing solvent, it is also possible to use naphtha with an appropriate (δ) value obtained by distillation after secondary hydrogenation, as detailed below. For example, it is very advantageous that the deashing solvent can be supplied in a closed system from the hydrogenation and liquefaction plant itself. That is, the purified SRC after deashing is subjected to secondary hydrogenation treatment as described above, and then liquefied oil is recovered by distillation, but the (δ) value of the naphtha component in the liquefied oil is 2.
Since the subsequent hydrogenation conditions can be kept within the above-mentioned preferred range by controlling the conditions, this naphtha component can be recycled and used as a deashing solvent.

Incidentally, FIG. 2 shows a comparison of the solvent-soluble components in the primary hydrogenated SRC when cyclohexasan or secondary naphtha is used as the deashing solvent. However, the secondary naphtha has a (δ) value of 8.1 obtained by performing secondary hydrogenation at 400°C and distilling it, and the secondary naphtha obtained by performing secondary hydrogenation at 860°C and distilling it (δ). ) A secondary naphtha with a value of 8.9 was used. As is clear from Figure 2, when cyclohexane or secondary naphtha with a (δ) value of 8.1 is used, there is almost no loss of BS or HS in the primary hydrogenated SRC.
The I minute can be reduced to about 115. However, if a secondary naphtha with a too high δ) value is used, 65% of the BI
Approximately 96% of the amount has been mixed into the width of the refined SRC as a soluble component, making it impossible to achieve the object of the present invention.

By the way, the specific method of deashing using the above deashing solvent is not a limiting requirement of the present invention, and known filtration methods, centrifugation methods, gravity sedimentation methods, etc. can be employed. However, each of the above methods has advantages and disadvantages in terms of equipment, operability, separation efficiency, etc., so it may be selected and determined as appropriate depending on the site situation, but the most common method is the gravity sedimentation method.

Next, a series of hydrogenation and liquefaction processes including deashing and pre-asphaltene treatment as described above will be briefly explained based on the flow diagram of Fig. 8. There are no limitations to the embodiments, and all modifications and implementations that do not violate the spirit of the preceding and following paragraphs are included within the technical scope of the present invention. In the figure, square frames represent processing details, and parentheses represent substances. That is, a slurry obtained by mixing raw material lignite with a solvent is preheated if necessary, and then subjected to primary hydrogenation at high temperature and pressure in the presence of an iron-based catalyst. The size and amount of the slurry-forming solvent, the conditions for preheating and the primary hydrogenation reaction, etc. are not limiting requirements of the present invention.After the primary hydrogenation is completed, gas-liquid separation is performed under reduced pressure if necessary, and then Distillation fil is performed, in which the equilibrium solvent is recovered and S
RC is recovered and naphtha (mixed oil consisting of aromatic compounds, naphthenes, paraffins, etc.) is produced as a product.
is obtained. Since the SRC obtained by distillation (1) contains ash as described above, a deashing process is subsequently performed, but in the present invention, (δ) is used as a deashing solvent in this deashing process. An organic solvent having a value of 7.4 to 8.5 is used to remove pre-asphaltene components in SRC simultaneously with deashing, and to prevent deactivation of the hydrogenation catalyst in the next secondary hydrogenation step. In addition, when performing distillation (2) again after deashing and adding a step of recovering the deashing solvent added at the time of deashing, the recovered solvent can also be recycled as the deashing solvent. As a deashing solvent, naphtha obtained by distillation (3) after secondary hydrogenation is also used as described later, but initially, the naphtha with a predetermined (δ) value left at the end of the previous operation is used. Use naphtha or a separately prepared organic solvent, and after entering a certain running state, you can replenish the secondary naphtha to the extent that it makes up for the lack of recovered solvent obtained in distillation (2). .

The conditions for distillation f41 and distillation (2) are not particularly restricted, but as is clear from Figure 8, at least naphtha fraction (low boiling point fraction), equilibrium solvent (medium temperature fraction), and
It is desired that it can be fractionated into RC (high temperature distillate). The deashing conditions are not particularly limited as long as a deashing solvent with an appropriate (δ) value is used, but the most preferred conditions are as follows.

Temperature: 150 to 400°C, more preferably 180 to 800°C Pressure: 20 to 60 KFI/cm2 Amount of deashing solvent: 2 to 20 times, preferably 2.5 to 4 times (weight ratio) to the amount of SRC In the ash process, as mentioned above, the pre-asphaltene components in SRC are removed as much as possible together with the ash content, and m5Rc, which consists essentially of Bl, HI and H8, is removed without causing deactivation of the secondary hydrogenation catalyst.
becomes. Therefore, when secondary hydrogenation is performed by adding an equilibrium solvent and a rope for secondary hydrogenation to this, the SRC component that was not completely decomposed in the primary hydrogenation step is further subjected to hydrogen decomposition. Therefore, by subjecting this to distillation (3) to recover naphtha and medium oil, the yield of liquefied oil from raw brown coal can be greatly increased. The equilibrium solvent recovered in distillation (3) is recycled as a solvent for secondary hydrogenation, and a portion of the secondary naphtha is recycled as a solvent for deashing. It goes without saying that the (δ) value of the secondary naphtha returned as a deashing solvent should be in the range of 7.4 to 8.5, as is clear from the above explanation.

The flow diagram in Figure 4 shows another example, in which distillation (
The equilibrium solvent obtained in 3) is returned to the primary hydrogenation step, and distilled fl.
) is substantially the same as the example shown in FIG. 8, except that a part of the equilibrium solvent separated in step ) is extracted as a product.

Next, the hydrogenation conditions are not a limiting requirement of the present invention, and may be determined appropriately by taking into account the properties of the coking coal, the type and type of equilibrium solvent, the amount of H2 consumed, the type of catalyst, etc. Examples of conditions are as follows.

<Primary Hydrogenation> Temperature: 4Bθ ~ 480"C Pressure Ni 1 Catalyst - 280 Catalyst 2 Fe2O3+s Hydrogenation Degree: 8 ~ 496 <Secondary Hydrogenation> Temperature: 400°C or less Pressure Ni 1 5 0 ~ 2 8 0 Kg/ cm2G catalyst:
(Metal catalyst hydrogenation degree of Q-M□ system, Ni-Mo system, etc.: 3 to 4% Next, examples of the present invention will be shown.

In the case where the crude SRC obtained by the primary ice addition contains ash equivalent to 15% by weight and BI equivalent to 40% by weight, this crude SRC is introduced into the settling tank of 501-,
Naphtha, cyclohexane, or toluene with a (δ) of 8.1 obtained in distillation (3) was added at a weight ratio of 4 times the crude SRC, and deashing and preasphaltene were performed at a temperature of 250°C and a flow rate of 701/hr. Ta.

The results are shown in Table 2, and when deashing solvents (naphtha and cyclohexane) with (δ) values within the specified range were used, both the BI content and ash content in the deashing SRC were extremely small. However, if a solvent with too high (δ) value (toluene) is used, pre-asphaltene will be eluted during the deashing process, so B! It is clear that this is extremely harmful and leads to deactivation of the catalyst in the secondary hydrogenation process.

Table 2 The present invention is roughly constructed as described above, and in the deashing process, 2
Since pre-asphaltene, which causes deactivation of the secondary hydrogenation catalyst, can be removed as much as possible, the secondary hydrogenation efficiency can be maintained at a high level, and the recovery rate of liquefied oil from raw brown coal can be improved. I was able to increase it significantly. Furthermore, pre-asphaltenes can be removed simultaneously in the deashing process by simply setting the (δ) value of the deashing solvent, and there is no risk of deteriorating operability. Moreover, if a method of circulating secondary naphtha is adopted as a melting method for ashing, it is economical since there is no need to supply a commercially available deashing solvent from outside, providing an extremely practical technology. I was able to do that.

[Brief explanation of the drawing]

Figure 1 shows the solubility tNIL lameter (δ) of the deashing solvent.
Graph showing the relationship between and the amount of solvent-soluble components in SRC, 2nd
The figure shows the SRC that will be damaged if the type of deashing solvent is changed.
Figure 8.4 is a flow diagram showing an embodiment of the present invention. Applicant Kobe Co., Ltd.! RfIs place (and 4 others)

Claims (1)

[Claims] (1) Brown coal is mixed with a liquefaction solvent and a hydrogenation catalyst, and primary hydrogenation is performed at high temperature and pressure in the presence of hydrogen. The resulting hydrogenated product, solvent-refined coal, is deashed and fixed. In the two-stage hydrogenation and liquefaction method of lignite which is subjected to secondary hydrogenation using a bed hydrogenation catalyst, in the deashing step, the solubility parameter (δ) at 25° C. of the secondary hydrogenation product as a deashing solvent is 7.
A two-stage hydrogenation and liquefaction method for lignite, characterized in that a naphtha fraction having a molecular weight of 4 to 8.5 is used to deash and remove pre-asphaltene components in solvent-refined coal. (2. A two-stage hydrogenation and liquefaction method for lignite according to claim 1, in which a naphtha fraction obtained by distilling a secondary hydrogenation product is recycled as a deashing solvent.