CN104119207A - Method for preparation of ethylene glycol by catalytic conversion of carbohydrate - Google Patents

Abstract

The invention provides a method for preparing ethylene glycol by catalytic conversion of carbohydrates. The method uses carbohydrates as reaction raw materials, uses water as a solvent, and uses one or both of the simple substance or compound of lanthanum and group 8, 9, and 10 transition metals iron, cobalt, nickel, ruthenium, rhodium, palladium, iridium, and platinum. The catalyst composed of the above two is a composite catalyst, which undergoes a one-step catalytic conversion process under hydrothermal conditions of 120-300°C and hydrogen pressure of 1-13MPa to realize the preparation of ethylene glycol with high efficiency, high selectivity and high yield from cellulose. Compared with the existing synthetic route of petroleum-based ethylene glycol, the reaction provided by the invention has the advantages of renewable resources, high atom economy and environmental friendliness. In addition, compared with other technologies that use biomass as raw material to produce polyols, this process has the advantages of less catalyst consumption, good circulation, and less corrosion to reaction equipment.

Description

Method for preparing ethylene glycol by catalytic conversion of carbohydrates

technical field

The invention relates to a method for catalytic conversion of carbohydrates to ethylene glycol, in particular to the process of preparing ethylene glycol through catalytic conversion of carbohydrates under hydrothermal conditions.

Background technique

Ethylene glycol is an important energy liquid fuel and a very important raw material for polyester synthesis (polyethylene terephthalate (PET), polyethylene naphthalate (PEN)), and can also be used as Antifreeze, lubricants, plasticizers, and surfactants are widely used organic chemical raw materials.

At present, the industrial production of ethylene glycol mainly adopts the route of petroleum raw materials, that is, ethylene oxide is obtained after epoxidation of ethylene, and then ethylene glycol is obtained by hydration (Document 1: Cui Xiaoming, Overview of ethylene glycol production and development at home and abroad, Chemical Industry, 2007, 25, (4), 15-21. Literature 2: Process for preparing ethanediol by catalyzing epoxyethanehydration, Patent No.CN1463960-A; CN1204103-C). The synthesis method relies on non-renewable petroleum resources, and the production process includes selective oxidation or epoxidation steps, which are technically difficult, low in efficiency, with many by-products, high energy consumption and serious pollution.

The use of renewable biomass to prepare ethylene glycol can reduce human dependence on fossil energy materials, and is conducive to the realization of environmental friendliness and sustainable economic development. Carbohydrates such as cellulose are the renewable resources with the largest yield on the earth, with very abundant sources and very low utilization costs. The use of cellulose and other carbohydrates to produce ethylene glycol can not only open up a new synthetic route, but also realize the production of high economic value products from cheap carbohydrates. Moreover, since some carbohydrates such as cellulose cannot be eaten by humans, they will not affect human food security.

At present, ethylene glycol is prepared by catalytic hydrogenation conversion of cellulose under hydrothermal conditions (Document 1: Direct catalytic conversion of cellulose into ethylene glycolusing nickel-promoted tungsten carbide catalysts, Angew.Chem.Int.Ed.2008,47,8510- 8513; Document 2: Transition metal-tungstenbimetallic catalysts for the conversion of cellulose into ethylene glycol, ChemSusChem2010, 3, 63-66; Document 3: CN102190562A, a method for preparing ethylene glycol from polyols). The method uses a composite catalyst composed of a tungsten-based catalyst and a hydrogenation catalyst to catalyze the conversion of cellulose to obtain 60-75% ethylene glycol.

The method provided by the present invention uses carbohydrates as raw materials, uses water as the reaction medium, and under the action of a binary catalyst composed of a lanthanum-based catalyst and transition metals of groups 8, 9, and 10, through a one-step reaction process, cellulose can be realized. Efficient conversion to ethylene glycol. The method not only has simple operation and low cost, but also has less catalyst consumption, good circulation and little corrosion to reaction equipment.

Contents of the invention

The object of the present invention is to provide a kind of fast, high-efficiency catalytic conversion carbohydrate to the method for ethylene glycol, and this method is simple to operate compared with conventional process, and cost is low, and environment is friendly, and catalyst consumption is few, and recyclability is good, etc. characteristics.

In order to achieve the above object, the technical scheme adopted by the present invention is: use carbohydrates as reaction raw materials, carry out catalytic hydrogenation reaction in water in a closed high-pressure reactor, the catalyst adopted is a composite catalyst, including catalyst A and catalyst B, catalyst The active ingredient of A is one or two or more of the simple substance or compound of lanthanum, and the active ingredient of catalyst B is the transition metal iron, cobalt, nickel, ruthenium, rhodium, palladium, iridium, platinum of the 8th, 9th, and 10th groups One or more of them are reacted under stirring in the reactor; before the reaction, the reactor is filled with hydrogen, the reaction temperature is ≥120°C, and the reaction time is not less than 5 minutes;

During use, the mass content of catalyst A in the system (calculated by metal lanthanum) is 0.001%-10%, and the weight ratio of the metal active component of catalyst B to the active component of catalyst A (calculated by metal lanthanum) is 0.01-200 times range.

The more preferred initial hydrogen pressure in the reactor at room temperature is 1-12MPa, the more preferred reaction temperature is 120-300°C, and the reaction time is 0.5h-5h; more preferably, the initial pressure of filling hydrogen in the reactor before the reaction is 3- 7MPa; the reaction temperature is 200-280°C, and the reaction time is 0.5h-3h.

Catalyst A is a non-supported catalyst, which can be one or more of lanthanum oxides, hydroxides, and salts, and the mass content in the entire system (calculated as metal lanthanum) is 0.001%-10%; the catalyst A can also be a supported catalyst, the active component is carried on the carrier, and the carrier is a composite carrier of activated carbon, alumina, silicon oxide, silicon carbide, zirconia, zinc oxide, titanium dioxide or more than two kinds, the active group The content of the sub-metal (calculated as metal lanthanum) on the catalyst is 0.01%-50wt%.

Catalyst B is a non-supported catalyst, a skeleton metal catalyst with the active component as the catalyst skeleton. Catalyst B can also be a supported catalyst, and the active component is loaded on a carrier, and the carrier is a composite carrier of one or more of activated carbon, alumina, silicon oxide, silicon carbide, zirconia, zinc oxide, and titanium dioxide; The content of the component metals on the catalyst is 0.05%-50wt%.

The composite catalyst can be a single supported catalyst, that is, one or more of the single substance or compound of the catalyst A lanthanum is used as a carrier, and the active component of the catalyst B is loaded on the catalyst A as the carrier, and the active component metal B is placed on the carrier. The content on the catalyst is 1-50wt%;

Or the active components of catalyst A and catalyst B are jointly supported on the same carrier, and the carrier is a composite carrier of one or more of activated carbon, alumina, silicon oxide, silicon carbide, zirconia, zinc oxide, and titanium dioxide; active The content of component metal B on the catalyst is 0.05%-50wt%, and the content of active component metal A on the catalyst is 0.05%-40wt%.

The amount of cellulose and water used as the reaction raw material can be stirred under the condition that the reaction material is partially or completely liquid under the reaction condition, which can make the reactant heated evenly and avoid the burning of the raw material caused by excessive local temperature.

The carbohydrates are one or more of cellulose, starch, hemicellulose, Jerusalem artichoke, sucrose, glucose, mannose, fructose, fructan, xylose, arabinose, and soluble xylooligosaccharides.

The simple substance or compound of lanthanum is metal lanthanum, lanthanum halide (fluorine, chlorine, bromine, iodine), lanthanum hydroxide, lanthanum nitrate, lanthanum sulfate, lanthanum carbonate, basic lanthanum carbonate, halogen (fluorine, chlorine, bromine, iodine) One or more of lanthanum acid, high halogen (fluorine, chlorine, bromine, iodine) lanthanum acid, lanthanum oxalate, and lanthanum phosphate.

The preferred weight concentration of catalyst A in the system is 0.01%-1%; the preferred weight ratio of the metal active component of catalyst B to the active component of catalyst A (calculated by the weight of metal lanthanum) during use is 0.1-100 times range between.

The present invention has following advantage:

1. Cellulosic carbohydrates, which are the most productive biomass in nature, are used as raw materials, which have a wide range of sources, and have the advantages of low cost and no competition for food and land. Moreover, compared with the use of ethylene as a raw material in the existing ethylene glycol industrial synthesis route, the reaction process provided by the present invention does not consume fossil resources, has the advantage of renewable raw material resources, meets the requirements of sustainable development, and is beneficial to waste utilization, It is of great significance to increase farmers' income.

2. Under the action of the composite catalyst, the selectivity of ethylene glycol is good, and at the same time, the amount of catalyst used in the process is small and the cycle is good.

3. Since the lanthanum-based catalyst is weakly alkaline in aqueous solution, long-term use is less corrosive to the reaction device, which can greatly save equipment investment, and has a good industrial application prospect.

The present invention will be described in detail through specific examples below, but these examples do not limit the content of the present invention.

Detailed ways

Example 1

Preparation of lanthanum-based catalysts: non-supported catalysts such as lanthanum oxides, hydroxides, and salts are commercial drugs purchased directly, and the purity grades of the drugs are all analytically pure. In the supported catalyst, the active component is loaded on the carrier, and the carrier is a composite carrier of one or more of activated carbon, alumina, silicon oxide, silicon carbide, zirconia, zinc oxide, and titanium dioxide, and the metal salt of lanthanum (The anion can be one or more of nitrate, chloride or bromide) The aqueous solution is loaded onto the carrier by equal volume impregnation, dried overnight at 120°C, and then calcined at 700°C for 4h under N2 atmosphere.

Example 2

Preparation of metal hydrogenation catalyst: use one or more of activated carbon, alumina, silicon oxide, silicon carbide, zirconia, zinc oxide, and titanium dioxide as a carrier, and chloroplatinic acid, palladium chloride, ruthenium chloride, and rhodium chloride The aqueous solutions of iridium chloride, nickel nitrate, iron nitrate and cobalt nitrate were respectively loaded on the carrier by equal volume impregnation method, and dried overnight at 120°C.

The above catalysts loaded with ruthenium, rhodium, palladium, iridium, platinum and other precious metals need to be reduced with hydrogen at 250°C for 2 hours and passivated for 4 hours under 1% O2/N2 (V/V) atmosphere; , Cobalt and other non-noble metal catalysts need to be reduced with hydrogen at 450°C for 2 hours and passivated for 4 hours under 1% O2/N2 (V/V) atmosphere before use.

Example 3

Preparation of lanthanum oxide-supported nickel catalyst: Weigh 1.5g La2O3, 0.8g Ni(NO3)2 6H2O, dissolve nickel nitrate in 20ml water, then add La2O3 into the completely dissolved nickel nitrate solution, and place in a water bath at 25°C , and stirred for 12h until the solution evaporated completely. Dry in an oven at 120°C for 8h, calcinate at 500°C for 2h in N2 atmosphere, and then reduce for 5h at 500°C in H2 atmosphere.

Example 4

Preparation of the co-supported catalyst: Using multiple equal-volume impregnation methods, weigh 1.5g activated carbon, 0.4g La(NO3)3 6H2O, 0.8g Ni(NO3)2 6H2O, first La(NO3)3 6H2O Dissolve 6H2O in water, then pour the activated carbon into the lanthanum nitrate solution, put it in an oven at 120°C to dry overnight, and roast it at 700°C in N2 atmosphere for 4 hours, then impregnate the calcined catalyst in Ni(NO3)2·6H2O solution, Let it stand at room temperature for 12 hours, put it in an oven at 120°C to dry overnight, bake at 700°C for 4 hours under N2 atmosphere, and finally reduce it at 700°C for 4 hours.

Example 5

Catalytic conversion experiment: Add 0.25g of carbohydrates, a certain mass of composite catalyst and 25ml of water into a 75ml reactor, then pass in hydrogen gas to replace the gas six times, fill it with hydrogen to 5MPa, raise the temperature to a certain temperature, and react for 30-240min. After the reaction was completed, the temperature was lowered to room temperature, and the centrifuged supernatant liquid was analyzed and detected by high-performance liquid chromatography. In the product yield, only the target products ethylene glycol, propylene glycol and hexahydric alcohols (including sorbitol and mannitol) are calculated.

Example 6

Comparison of the catalytic conversion results of microcrystalline cellulose under different catalysts, including single metal catalysts and composite catalysts. In the composite catalyst, catalyst A is lanthanum hydroxide, catalyst B is a hydrogenation catalyst of different metals, and the reaction conditions are the same as in Example 5.

Table 1 Results of catalytic conversion of cellulose on different catalysts

(The mass of catalyst A is 0.1g; the mass of catalyst B is 0.15g; the reaction temperature is 245°C, and the reaction time is 30min)

As shown in Table 1, the composite catalyst has a promoting effect on the generation of ethylene glycol. Comparing the changes in the yield of ethylene glycol and hexahydric alcohol before and after adding lanthanum hydroxide, it can be seen that the presence of lanthanum hydroxide promotes the yield of ethylene glycol. increased, the yield of hexavalent alcohols decreased significantly.

Example 7

Among the composite catalysts, catalyst A is a lanthanum-containing compound, and catalyst B is Ni/AC. The reaction conditions are the same as in Example 5, and the catalytic conversion results of cellulose on various composite catalysts (Table 2).

Table 2 Effect of different lanthanum precursors on the catalytic conversion of cellulose

(The mass of catalyst A is 0.1g; the mass of catalyst B is 0.15g; the reaction temperature is 245°C, and the reaction time is 30min)

As shown in Table 2, using different lanthanum-containing compounds as catalysts, the yield of ethylene glycol obtained by adding lanthanum oxide and lanthanum hydroxide is much higher than that of other lanthanum compounds within 30 minutes, but at this time the cellulose has not yet completely transform.

Example 8

Among the composite catalysts, catalyst A is lanthanum hydroxide, and catalyst B is Ni/AC. The reaction conditions are the same as in Example 5, and the catalytic conversion results of the composite catalytic system on different carbohydrates (Table 3).

Table 3 Catalytic conversion results of composite catalysts on different carbohydrates

(The mass of catalyst A is 0.005g; the mass of catalyst B is 0.15g; the reaction temperature is 245°C, and the reaction time is 120min)

As shown in Table 3, this composite catalyst has different selectivities on different carbohydrates, and the selectivity to C2 and C3 alcohols is better than that of C6 alcohols and C4 alcohols, indicating that this composite catalyst has a certain bond-breaking effect, and the fiber The yield of ethylene glycol obtained from raw materials is higher than that of other carbohydrates.

Example 9

Effect on reaction time. Catalyst A is La(OH)3, catalyst B is 10%Ni/AC, and the catalytic conversion results of cellulose under different reaction times (Table 4). Except that the reaction time is different, the reaction conditions are the same as in Example 5.

Table 4 Catalytic conversion results of cellulose on composite catalysts under different reaction times

(The mass of catalyst A is 0.1g; the mass of catalyst B is 0.15g; the reaction temperature is 245°C)

As shown in Table 4, within a certain time range, this composite catalytic system has a good yield of ethylene glycol. The preferred time is 1h-2.5h.

Example 10

The effect of reaction temperature. Catalyst A is La(OH)3, catalyst B is 10%Ni/AC, the results of catalytic conversion of cellulose at different reaction temperatures (Table 5), and the reaction conditions are the same as in Example 5.

Table 5 Catalytic conversion results of cellulose on composite catalysts at different reaction temperatures

(The mass of catalyst A is 0.1g; the mass of catalyst B is 0.15g; the reaction time is 110min)

As shown in Table 5, within a certain temperature range, this composite catalytic system has a good yield of ethylene glycol. The preferred temperature is 230-260°C.

Example 11

Catalyst A dosage effect. Catalyst A is La(OH)3, catalyst B is 10%Ni/AC, the results of catalytic conversion of cellulose with different amounts of catalyst A (Table 6), and the reaction conditions are the same as in Example 5.

Table 6 Catalytic conversion results of cellulose on the composite catalyst under different amounts of catalyst A

(The mass of catalyst B is 0.15g; the reaction temperature is 245°C, and the reaction time is 110min)

As shown in Table 6, when the amount of catalyst A is reduced to 1 mg, a good yield of ethylene glycol can still be obtained, indicating that the catalytic system has high activity, and the optimal weight concentration of catalyst A in the system is 0.01-0.5 %.

Example 12

Catalyst 10%Ni/La2O3 cycle test. The active components of catalyst B were carried on catalyst A as a carrier, and the cycleability of this composite catalyst was examined (Table 7). The reaction conditions were the same as in Example 5.

Table 7 10%Ni/La2O3 recycling test results

(The mass of the catalyst is 0.15g, the reaction temperature is 245°C, and the reaction time is 150min)

Cycles Ethylene glycol yield% Propylene Glycol Yield% Hexahydric alcohol yield% first 42.6 13.2 2.0 the second time 45.7 13.3 2.5 the third time 46.5 13.8 6.1 the fourth time 45.0 13.3 5.9 the fifth time 38.0 12.1 6.3

As shown in Table 7, the first five cycles of the catalyst 10%Ni/La2O3 can obtain a higher yield of ethylene glycol, and the optimal number of cycles for this composite catalyst is 5 times.

The binary composite catalytic system in the present invention can realize efficient conversion of carbohydrates into ethylene glycol. This method is not only simple to operate and low in cost, but also has the advantages of less catalyst consumption, good circulation, and less corrosion to reaction equipment.

Claims (9)

1. a method for preparing ethylene glycol by catalytic conversion of carbohydrates, is characterized in that: it is reaction raw material with carbohydrate, in airtight autoclave, carries out catalytic hydrogenation reaction in water, and the catalyzer that adopts is composite catalyst, Including Catalyst A and Catalyst B; the active ingredient of Catalyst A is one or two or more of the simple substance or compound of lanthanum, and the active ingredient of Catalyst B is the transition metal iron, cobalt, nickel, ruthenium of Group 8, 9, 10 , rhodium, palladium, iridium, and platinum; the reaction is carried out with stirring in a closed high-pressure reactor; the reactor is filled with hydrogen before the reaction, the reaction temperature is ≥ 120 ° C, and the reaction time is not less than 5 minutes; During use, the mass content of catalyst A (calculated as metal lanthanum) in the reaction system is between 0.001% and 10%, and the weight ratio of the metal active component of catalyst B to the active component of catalyst A (calculated as metal lanthanum) is between 0.001% and 10%. Between 0.01-200 times the range. 2. according to the described method of claim 1, it is characterized in that: hydrogen is filled in the reactor before reaction, and the initial pressure of hydrogen is 1-12MPa when room temperature; allow. 3. The method according to claim 1, characterized in that: the preferred reaction temperature is 200-280°C, the preferred initial pressure of hydrogen in the reactor at room temperature is 3-7MPa, and the preferred reaction time is 0.5h-3h. 4. according to the described method of claim 1, it is characterized in that: The catalyst A is a non-supported catalyst, which can be one or more than two kinds of single substance or compound of lanthanum, and the mass content in the whole reaction system (calculated as metal lanthanum) is 0.001%-10%; Or, the catalyst A is a supported catalyst, and the active component is carried on a carrier, and the carrier is a carrier of activated carbon, alumina, silicon oxide, silicon carbide, zirconia, zinc oxide, titanium dioxide or a composite of two or more The carrier, the content of the active component metal (calculated as metal lanthanum) on the catalyst is 0.01%-50wt%. 5. according to the described method of claim 1, it is characterized in that: The catalyst B is a non-supported catalyst, a skeleton metal catalyst with a metal active component as a catalyst skeleton; Or, the catalyst B is a supported catalyst, and the active component is carried on a carrier, and the carrier is activated carbon, alumina, silicon oxide, silicon carbide, zirconia, zinc oxide, titanium dioxide, or a composite of two or more Carrier; the content of the active component metal on the catalyst is 0.05%-50wt%. 6. according to the described method of claim 1, it is characterized in that: described composite catalyst can be single supported catalyst, is about to use catalyst A single substance or one or two or more in the compound of lanthanum as carrier, catalyst B The active component is carried on the catalyst A as a carrier, and the content of the active component B metal on the catalyst is 1%-50wt%; Or the active components of catalyst A and catalyst B are jointly supported on the same carrier, and the carrier is a composite carrier of one or more of activated carbon, alumina, silicon oxide, silicon carbide, zirconia, zinc oxide, and titanium dioxide; active The content of component metal B on the catalyst is 0.05%-50wt%, and the content of active component metal A on the catalyst is 0.05%-40wt%. 7. according to the described method of claim 1, it is characterized in that: the consumption of reaction raw material and water is partly or completely liquid state to get final product under reaction condition; The carbohydrates are one or more of cellulose, starch, hemicellulose, Jerusalem artichoke, sucrose, glucose, mannose, fructose, fructan, xylose, arabinose, and soluble xylooligosaccharides. 8. according to the described method of claim 1 or 4, it is characterized in that: The simple substance or compound of lanthanum is metal lanthanum, lanthanum halide (fluorine, chlorine, bromine, iodine), lanthanum hydroxide, lanthanum nitrate, lanthanum sulfate, lanthanum carbonate, basic lanthanum carbonate, halogen (fluorine, chlorine, bromine, iodine) One or more of lanthanum acid, high halogen (fluorine, chlorine, bromine, iodine) lanthanum acid, lanthanum oxalate, and lanthanum phosphate. 9. according to the described method of claim 1, it is characterized in that: the preferred weight concentration of catalyst A is at 0.01%-1% in the system; Calculation) The preferred weight ratio during use is between 0.01-100 times.