CN105693659B - A kind of preparation method of tetrahydrofurfuryl alcohol - Google Patents

Abstract

The present invention reports a method for preparing tetrahydrofurfuryl alcohol by hydrogenation of furfural in water phase. In the water phase reaction medium, furfural is under the action of nickel-based catalyst supported by alkaline earth metal modified alumina at 0.5-10MPa In a hydrogen atmosphere, at a temperature of 80-180°C, one-step hydrogenation produces tetrahydrofurfuryl alcohol. The catalyst used to prepare tetrahydrofurfuryl alcohol by catalyzing the aqueous phase hydrogenation of furfural is a metal-supported catalyst, and the carrier is an alumina carrier modified by one or more alkaline earth metals; the alkaline earth metal is one of Mg, Ca, Sr, and Ba Or two or more; using water as a solvent conforms to the principles of green chemistry and reduces costs. The catalyst provided by the invention can realize the high-yield preparation of tetrahydrofurfuryl alcohol in the water phase, reduces the reaction cost and separation difficulty, and the yield of tetrahydrofurfuryl alcohol can reach more than 99%.

Description

A kind of preparation method of tetrahydrofurfuryl alcohol

technical field

The invention belongs to the field of organic chemistry, and in particular relates to a preparation method of tetrahydrofurfuryl alcohol and its application in catalytic furfural aqueous phase hydrogenation to prepare tetrahydrofurfuryl alcohol.

Background technique

Tetrahydrofurfuryl alcohol (also known as tetrahydrofuran methanol), is an important organic chemical raw material with a wide range of uses. For example, it can be used as a raw material for the preparation of organic chemicals such as pyran, pyridine, tetrahydrofuran, lysine, pentylene glycol, and γ-valerolactone; it can also be used as a solvent for coatings, resins, and oils; it can also be used for the preparation of decolorization Agents, plasticizers, insecticides, antifreeze, herbicides, etc.

At present, the preparation methods of tetrahydrofurfuryl alcohol are mainly divided into two-step hydrogenation method and one-step hydrogenation method of furfural. In the first step of the two-step hydrogenation method, furfural is hydrogenated to furfuryl alcohol. This step of hydrogenation mainly uses copper-based catalysts, including traditional copper-chromium catalyst systems and new chrome-free copper-based catalyst systems. For example, the copper-based systems disclosed in patents US2094975, CN1562477, CN1410161 and CN1256965 can all obtain furfuryl alcohol yields above 99%. The second step of the two-step hydrogenation method is to hydrogenate furfuryl alcohol to generate tetrahydrofurfuryl alcohol. This step reaction mainly uses nickel-based catalysts, mainly including skeleton nickel catalysts, supported nickel catalysts and amorphous alloy nickel-based catalysts. For example, the furfuryl alcohol hydrogenation catalyst disclosed in patents CN1847234A, CN1341483A and CN1789257A can obtain a tetrahydrofurfuryl alcohol yield of more than 97%. The two-step hydrogenation method to prepare tetrahydrofurfuryl alcohol can obtain a very high total yield of tetrahydrofurfuryl alcohol, which is currently the main production method used in industry. However, the two-step hydrogenation method has the disadvantages of high energy consumption, serious pollution of the copper-chromium catalyst, instability of the framework nickel catalyst, easy ignition when exposed to air, and poor safety. Therefore, in recent years, people's research focus has turned to the direct hydrogenation of furfural to prepare tetrahydrofurfuryl alcohol.

Directly using furfural as raw material to prepare tetrahydrofurfuryl alcohol by one-step hydrogenation shortens the preparation process of tetrahydrofurfuryl alcohol, which is beneficial to reduce energy consumption and cost. Keiichi Tomishige et al. used Ni-Pd/SiO ₂ as a catalyst to hydrogenate furfural in water phase under relatively mild conditions (40°C, 8MPa H ₂ ), and the yield of tetrahydrofurfuryl alcohol reached 96% (CatalysisCommunications 2010, 12:154–156). Chandrashekhar V.Rode et al used isopropanol as a solvent, and at 220°C and 500psi on a Pd/MFI catalyst, furfural was hydrogenated in one step to obtain a 95% tetrahydrofurfuryl alcohol yield (ACSSustainable Chemistry & Engineering 2014, 2, 272-281). Patent CN201110434841.X discloses a preparation method of Ru-M/TiO ₂ catalyst and its application in the synthesis of tetrahydrofurfuryl alcohol. Under 80°C and 1MPa hydrogen pressure, the yield of tetrahydrofurfuryl alcohol reaches more than 99%. At present, many of the methods for preparing tetrahydrofurfuryl alcohol by one-step reaction of furfural reported in the literature have good reaction results. However, most of them use noble metal catalysts, and many of them use alcohol as the reaction solvent, which increases the cost of the reaction and the difficulty of product separation.

Contents of the invention

The object of the present invention is to provide a kind of adopting non-precious metal catalyst, the method for preparing tetrahydrofurfuryl alcohol in one step by furfural in aqueous phase.

Technical scheme of the present invention is:

In an aqueous reaction medium, furfural is hydrogenated in the next step to generate tetrahydrofurfuryl alcohol under the action of an alkaline earth metal-modified alumina-supported nickel-based catalyst.

The catalyst used to prepare tetrahydrofurfuryl alcohol by catalyzing the aqueous phase hydrogenation of furfural is a metal-supported catalyst, and the carrier is an alumina carrier modified by one or more alkaline earth metals; the alkaline earth metal is one of Mg, Ca, Sr, and Ba or two or more;

The preparation method of the carrier adopts the co-precipitation method: the precipitation agent is added dropwise to the aqueous solution of aluminum nitrate and alkaline earth metal nitrate to pH 9-12; the modified alumina carrier is obtained after standing at room temperature, washing, drying and roasting; the nitric acid in the solution The aluminum concentration is 0.1-2mol/L, and the precipitant is selected from NaOH, KOH, NH ₃ ·H ₂ O, Na ₂ CO ₃ , K ₂ CO ₃ , (NH ₄ ) ₂ CO ₃ , CO(NH ₂ ) ₂ one or more kinds; the drying temperature is 60-140°C, the roasting temperature is 500-800°C; the molar concentration of alkaline earth metal nitrate is 1-20% of that of aluminum nitrate.

The catalyst for preparing tetrahydrofurfuryl alcohol by catalyzing the aqueous phase hydrogenation of furfural selects Ni as the active component, the loading amount of the active component is 1-20% of the total mass of the catalyst, and the molar ratio of the substrate furfural to Ni is maintained at 5-100 in the amount of the catalyst.

The hydrogenation reaction of furfural is carried out in water medium, and the mass concentration of furfural aqueous solution is 5-50%.

The hydrogen pressure of the furfural hydrogenation reaction is 0.5-10MPa, the reaction temperature is 80-180°C, and the reaction time is 0.5-24h.

Alumina is a catalyst carrier widely used in industrial catalysts. It is cheap, has high heat resistance, and has good affinity for active components. The alkaline earth metal modified alumina coprecipitation method of the invention is prepared, and the operation is simple and the repeatability is good. The specific preparation method is as follows:

Add the precipitant dropwise to the aqueous solution of aluminum nitrate and alkaline earth metal nitrate at a certain concentration until the pH is 9-12. The modified alumina carrier is obtained through the steps of standing at room temperature, washing, drying, roasting and the like. The concentration of aluminum nitrate is 0.1-2mol/L, and the precipitant is NaOH, KOH, NH ₃ ·H ₂ O, Na ₂ CO ₃ , K ₂ CO ₃ , (NH4) ₂ CO ₃ , CO(NH ₂ ) ₂ and so on. The drying temperature is 60-140°C, and the calcination temperature is 500-800°C. The molar concentration of alkaline earth metal nitrate is 1-20% of that of aluminum nitrate.

The catalyst used in the hydrogenation of furfural is a metal-supported catalyst. The active component is Ni, and the auxiliary agent is selected from one or more of Mn, Fe, Co, Cu, Zn, La, and Ce. In the literature (Catalysis Communications2010,12:154-156; ACS Sustainable Chemistry & Engineering 2014,2,272-281; CN201110434841.X) reported in the method for preparing tetrahydrofurfuryl alcohol by one-step reaction of furfural, many have good reaction results, but Most of them use noble metal catalysts, which increases the cost of the reaction.

The reaction adopts a liquid-phase hydrogenation method with water as a solvent. A typical reaction step is as follows: a furfural water mixture with a concentration of 5-50wt% and a catalyst are put into a high-pressure reaction kettle. After replacing the gas in the reactor with hydrogen, raise the temperature to 80-180°C and fill with 0.5-10MPa hydrogen, and start to react for a certain period of time.

Beneficial effects of the present invention

Alcohols are mostly used as solvents in the liquid-phase hydrogenation routes reported in current literature and patents (Applied Catalysis A: General 1998, 171: 117-122; ACS Sustainable Chemistry & Engineering 2014). Compared with organic solvents such as alcohol, water is the safest and cheapest solvent. The use of water as a solvent conforms to the principles of green chemistry and reduces costs. The catalyst provided by the invention can realize the high-yield preparation of tetrahydrofurfuryl alcohol in the water phase, and reduces the reaction cost and separation difficulty.

The invention provides a technical route for preparing tetrahydrofurfuryl alcohol by direct catalytic hydrogenation reduction of furfural in water phase by adopting a nickel-based catalyst. This route does not use a noble metal catalyst, and directly converts furfural into tetrahydrofurfuryl alcohol in one step. At the same time, water is used as a solvent, which conforms to the principle of green chemistry. Compared with the methods reported in literature, the invention is innovative and has important application prospects.

Description of drawings

Figure 1. Product gas chromatogram. (Example 9) (t=6.142min tetrahydrofurfuryl alcohol, t=8.398min internal standard durene).

Detailed ways

The following examples will help to understand the present invention, but the content of the present invention is not limited thereto.

Examples 1-12

Preparation of the carrier:

A certain amount of Al(NO ₃ ) ₃ ·9H ₂ O and M(NO ₃ ) ₂ (M=Mg, Ca, Sr, Ba) was weighed and dissolved in 100 mL deionized water to keep the M/Al molar ratio at n%. Then dilute to 250 mL with deionized water. Under the condition of stirring, an aqueous solution of precipitating agent is added dropwise to the above solution until the pH of the solution is 8-9. Stirring was continued for 4h, and the mixture was allowed to stand at room temperature for 24h. The above precipitate was centrifuged and washed 5 times, and then dried in an oven at 120°C for 12 hours. The dried precipitate was calcined at 600 °C for 6 h in a muffle furnace. The MO-Al ₂ O ₃ -n support (where n% is the molar ratio of M/Al, M=Mg, Ca, Sr, Ba) is obtained.

Preparation of Ni supported catalyst

A certain amount of Ni(NO ₃ ) ₂ ·6H ₂ O was weighed to make the Ni loading amount 10wt%, added into deionized water and stirred to dissolve. The alumina support prepared above was added to the nickel nitrate solution. Stir well to form a paste, let stand for 10 hours, dry at 120°C, then bake at 500°C for 4 hours, and activate in hydrogen atmosphere at 600°C for 2 hours before use.

The catalytic reaction was carried out in a 50ml stainless steel reactor. Add 0.1g of catalyst, 1.5g of furfural and 8.5g of water into a stainless steel autoclave with polytetrafluoroethylene lining. After closing the reactor, replace the gas in the reactor with hydrogen four times, control the temperature to 140°C with a temperature controller, fill in hydrogen to 4MPa, and start the stirring reaction for 4h. During the reaction process, the pressure was kept constant, the hydrogenation reaction was completed, and after cooling and releasing the pressure, the samples were analyzed by gas chromatography. The reaction time and results are shown in Table 1.

Table 1 Effect of carrier preparation conditions on furfural hydrogenation performance

Examples 13-17

Two kinds of alkaline earth metal nitrate solutions were added during the preparation of the carrier in Example 3, so that the general structural formula of the prepared catalyst was Ni/M ₁ OM ₂ O-Al ₂ O ₃ , wherein M ₁ and M ₂ were two different Alkaline earth metal, the two molar contents are n ₁ % and n ₂ % respectively, other conditions are the same as Example 3, and the reaction results are shown in Table 2.

Table 2 The effect of carrier components on the hydrogenation performance of furfural

Examples 17-21

Adjust the nickel nitrate quality and carrier quality in embodiment 9, make the loading of nickel be x%, and change the molar ratio of furfural and Ni to be y;

Table 3 Effect of catalyst loading and product dosage on furfural hydrogenation performance

Examples 22-28

Change conditions such as temperature, pressure and furfural concentration in embodiment 9, other are all with embodiment 9, and reaction result is shown in table 4.

The influence of table 4 reaction conditions on furfural hydrogenation performance

In the present invention, furfural is converted into tetrahydrofurfuryl alcohol in one step, and the yield of tetrahydrofurfuryl alcohol can reach more than 99%.

Claims (4)

1. a preparation method of tetrahydrofurfuryl alcohol, characterized in that: in the aqueous reaction medium, furfural generates tetrahydrofurfuryl alcohol in the next step of hydrogenation in the action of nickel-based catalyst supported by alkaline earth metal modified alumina; The catalyst used to prepare tetrahydrofurfuryl alcohol by catalyzing the aqueous phase hydrogenation of furfural is a metal-supported catalyst, and the carrier is an alumina carrier modified by one or more alkaline earth metals; the alkaline earth metal is one of Mg, Ca, Sr, and Ba or two or more; The preparation method of the carrier adopts the co-precipitation method: the precipitation agent is added dropwise to the aqueous solution of aluminum nitrate and alkaline earth metal nitrate to pH9-12; the modified alumina carrier is obtained after standing at room temperature, washing, drying and roasting; the aluminum nitrate in the solution The concentration is 0.1-2mol/L, and the precipitant is one of NaOH, KOH, NH ₃ ·H ₂ O, Na ₂ CO ₃ , K ₂ CO ₃ , (NH ₄ ) ₂ CO ₃ , CO(NH ₂ ) ₂ Or more than two kinds; the drying temperature is 60-140°C, and the roasting temperature is 500-800°C; the molar concentration of alkaline earth metal nitrate is 1-20% of that of aluminum nitrate. 2. according to the described preparation method of claim 1, it is characterized in that: the catalyzer that catalyzes furfural aqueous phase hydrogenation prepares tetrahydrofurfuryl alcohol selects Ni as active component, and active component load is 1-20% of catalyzer gross mass, The amount of catalyst used keeps the molar ratio of the substrate furfural to Ni at 5-100. 3. according to the described preparation method of claim 1, it is characterized in that: the hydrogenation reaction of furfural is carried out in water medium, and the mass concentration of furfural aqueous solution is 5-50%. 4. The preparation method according to claim 1, characterized in that: the hydrogen pressure of the furfural hydrogenation reaction is 0.5-10MPa, the reaction temperature is 80-180°C, and the reaction time is 0.5-24h.