Multifunctional tandem catalytic process for directly preparing methyl acetate / ethanol from synthesis gas

Abstract

The invention relates to a multifunctional tandem catalytic process for directly preparing methyl acetate / ethanol from synthesis gas. According to the process, a novel catalyst for preparing dimethyl ether from synthesis gas is prepared by adopting an impregnation method, and after the catalyst is sequentially connected with a dimethyl ether carbonylation catalyst and a hydrogenation catalyst in series, efficient directional synthesis of methyl acetate and ethanol is realized in a double-bed or three-bed sequential filling form. According to the invention, high CO conversion per pass, high methyl acetate selectivity and low acetic acid selectivity can be realized, and the problems of corrosion and difficult conversion of a subsequent hydrogenation system are effectively avoided; the multifunctional catalytic system provided by the invention is simple in preparation method and easy to realize industrial large-scale production.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical catalysis, and particularly relates to a multifunctional tandem catalyst system for the one-step tandem synthesis of methyl acetate / ethanol from syngas and its application. Background Art

[0002] At present, considering the rapid consumption of petroleum resources and the over-reliance of oil-poor countries and regions on petroleum resources, the catalytic conversion of syngas to C 2+ oxygenates as an alternative process has attracted extensive interest from researchers. The production of liquid fuels and high-value chemicals from syngas using inexpensive and readily available raw materials such as coal, natural gas, and biomass is of great significance for the transformation and diversified development of the global energy structure. C 2+ Oxygenates such as ethanol and methyl acetate are important raw materials, intermediates, and solvents in the chemical industry, and can also be directly applied to fields such as medicine and daily life. Among them, methyl acetate is an important chemical intermediate and an excellent low-toxicity solvent. Its further hydrogenation product, ethanol, as an alternative fuel and fuel additive, can effectively improve the combustion performance of gasoline and reduce environmental pollution. In addition, ethanol is widely used in industries such as the chemical industry, medicine, and public health as a low-toxicity, green chemical raw material, excellent solvent, and disinfectant.

[0003] Currently, the processes for synthesizing methyl acetate and ethanol from syngas mainly go through several key reaction steps such as hydrogenation of CO to methanol, carbonylation of methanol / dimethyl ether to acetic acid / methyl acetate, and hydrogenation of acetic acid / methyl acetate (as shown in Figure 1 ). All of the above process routes have the problems of long process flow, involving multiple key reactors and intermediate separation devices, resulting in relatively high fixed investment.

[0004] Recently, researchers have found that by taking advantage of the reaction characteristics during the conversion of syngas and coupling multifunctional catalysts in series, it is possible to directly convert syngas to methyl acetate / ethanol in a single reactor, and obtain a relatively high single-pass conversion rate of syngas and a single C 2+The selectivity of oxygenates (literature: ACS Catal. 2023, 13, 10651 - 10660; Angew. Chem. 2018, 130, 12188 - 12192) greatly simplifies the process flow. In the tandem reaction, it mainly undergoes several key reaction steps including synthesis gas to methanol, methanol dehydration to dimethyl ether, water - gas shift reaction, dimethyl ether carbonylation to methyl acetate, and methyl acetate hydrogenation. However, in the reported work above, both the synthesis gas to methanol catalyst and the methanol dehydration to dimethyl ether catalyst are physically mixed in powder form, which makes the water produced in the methanol dehydration to dimethyl ether reaction unable to be converted in time through the water - gas shift reaction. The residual water will pass through the hydroformylation catalyst with the reaction gas flow, ultimately resulting in problems such as a high acetic acid content (>12%) in the dimethyl ether carbonylation product, low methyl acetate selectivity (<85%), low CO single - pass conversion rate (<10%), and strong corrosion in the subsequent hydrogenation system. Summary of the Invention

[0005] The object of the present invention is to provide a multifunctional tandem catalytic process for directly synthesizing methyl acetate / ethanol from syngas in view of the limitations in the current technology. This process prepares a novel synthesis gas to dimethyl ether catalyst by the impregnation method, and after sequentially connecting this catalyst with the dimethyl ether carbonylation catalyst and the hydrogenation catalyst, realizes the efficient and directional synthesis of methyl acetate and ethanol through the form of sequential loading in a two - bed or three - bed manner. The present invention can achieve a relatively high CO single - pass conversion rate and methyl acetate selectivity, a relatively low acetic acid selectivity, and effectively avoid the corrosion problem and difficult conversion problem in the subsequent hydrogenation system. The multifunctional catalytic system proposed by the present invention has a simple preparation method and is easy to realize industrial scale - up production. The process greatly simplifies the traditional process for synthesizing oxygenates such as methyl acetate and ethanol from syngas, is easy to load the catalyst, and is easy to operate and control. 2+ The process for oxygenates, the catalyst loading is easy, and the process is easy to operate and control.

[0006] The technical solution of the present invention is as follows:

[0007] A multifunctional tandem catalytic process for directly synthesizing methyl acetate / ethanol from syngas, which is one of the following two methods:

[0008] Method 1 includes the following steps:

[0009] Introduce the raw material gases H2 and CO into a fixed - bed reactor successively filled with a synthesis gas to dimethyl ether catalyst and a dimethyl ether carbonylation catalyst to obtain methyl acetate;

[0010] Among them, the reaction temperature is 200 - 350 °C, the reaction pressure is 1 - 6 MPa, the molar ratio of H2 / CO in the raw material gas is 0.2 - 4; the total reaction space velocity is 500 - 6000 mL / g cat / h; In the bed layer, the mass ratio is such that the synthesis gas to dimethyl ether catalyst in the upper layer: the dimethyl ether carbonylation catalyst in the lower layer = 1:(0.5 - 3);

[0011] Alternatively, Method 2 includes the following steps:

[0012] Feed the raw material gases H2 and CO into a fixed-bed reactor successively filled with a synthesis gas to dimethyl ether catalyst, a dimethyl ether carbonylation catalyst, and a hydrogenation catalyst to obtain ethanol;

[0013] Among them, the reaction temperature is 200 - 350 °C, the reaction pressure is 1 - 6 MPa, and the molar ratio of H2 / CO in the raw material gas is 0.2 - 4; the total reaction space velocity is 500 - 6000 mL / g cat / h; In the bed layer, the mass ratio is such that the synthesis gas to dimethyl ether catalyst in the upper layer: the dimethyl ether carbonylation catalyst in the middle layer: the hydrogenation catalyst in the lower layer = 1:(0.5 - 3):(0.5 - 2);

[0014] The dimethyl ether carbonylation catalyst mentioned above is a hydrogen-type molecular sieve catalyst with an eight-membered ring pore structure or a hydrogen-type molecular sieve catalyst modified with a metal promoter, preferably MOR, FER, SSZ-13, etc.;

[0015] The silicon-aluminum ratio of the hydrogen-type molecular sieve catalyst is: MOR (SiO2 / Al2O3 = 5 - 30), FER (SiO2 / Al2O3 = 5 - 30), SSZ-13 (SiO2 / Al2O3 = 5 - 40);

[0016] In the metal promoter-modified hydrogen-type molecular sieve catalyst mentioned above, a promoter metal element is also included; the promoter metal element is one or more of cerium, tin, gallium, iron, copper, nickel, silver, cobalt, zinc, and the loading is 0.5 - 10 wt.%.

[0017] The hydrogenation catalyst mentioned above is a typical supported copper-based methyl acetate hydrogenation catalyst prepared by an impregnation method, a deposition precipitation method, or an ammonia evaporation method;

[0018] In the supported copper-based methyl acetate hydrogenation catalyst mentioned above, the loading of the active metal Cu is 5 - 40 wt.%, preferably 10% - 30 wt.%;

[0019] The carrier is one or more of SiO2, CeO2, ZnO, ZrO2, Al2O3;

[0020] The promoter element is one or more of molybdenum, cobalt, zinc, manganese, iron, lanthanum, and the loading is 0.05 - 3 wt.%.

[0021] The preparation method of the synthesis gas to dimethyl ether catalyst includes the following steps:

[0022] (1) Mix a copper source, a zinc source, an aluminum source, a promoter precursor, and water by stirring to obtain an aqueous metal salt solution;

[0023] Among them, the molar ratio is: copper:zinc = 0.5 - 5:1, (copper + zinc):aluminum = 2 - 15:1;

[0024] The total molar concentration of copper, zinc, and aluminum in the aqueous metal salt solution is 0.5 - 2 mol / L;

[0025] The promoter precursor is one or more of nitrates, sulfates, acetates, phosphates, and chlorides of promoter active elements; the promoter active elements are one or more of silicon, chromium, iron, cobalt, nickel, gallium, zirconium, molybdenum, and cerium;

[0026] The mass of the promoter active element is 0.1 - 5 wt.% of the theoretical total mass of the syngas - to - dimethyl ether catalyst;

[0027] (2) Mix an alkali source and water by stirring to obtain an alkali solution with a molar concentration of 0.5 - 5 mol / L;

[0028] (3) Disperse the solid acid catalyst in water to obtain a suspension containing the solid acid catalyst; the concentration is 1 - 20 g / L;

[0029] (4) Drop the solutions obtained in steps (1) and (2) into the suspension obtained in step (3) simultaneously with a volume ratio of (0.5 - 2):1 under stirring to obtain a new suspension;

[0030] The mass ratio is: solid acid catalyst:metal oxide = 1:0.5 - 5;

[0031] (5) Stir and age the suspension obtained in step (4) at room temperature to 95 °C for 0 - 24 hours, then filter and wash until it is nearly neutral, and dry at 80 - 150 °C for 1 - 24 hours and calcine at 250 - 500 °C for 1 - 24 hours to obtain the required syngas - to - dimethyl ether catalyst.

[0032] The syngas - to - dimethyl ether catalyst includes a metal oxide (CuZnAlO x ), a solid acid, and a promoter active element.

[0033] The metal oxide CuZnAlO x is one or two of a ternary metal oxide mixture or a metal composite oxide obtained by calcining a copper source, a zinc source, and an aluminum source.

[0034] The copper source described in step (1) is one or more of copper nitrate, copper sulfate, and copper acetate; the zinc source is one or more of zinc nitrate, zinc sulfate, and zinc acetate; the aluminum source is one or more of aluminum nitrate, aluminum sulfate, and sodium meta - aluminate.

[0035] The alkali source described in step (2) is one or more of sodium carbonate, sodium bicarbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, and ammonia water.

[0036] The solid acid catalyst described in step (3) is one of common silicoaluminate molecular sieves (such as HZSM-5, H-β, HY, H-MOR, etc.), silicoaluminophosphate molecular sieves (such as SAPO-11, SAPO-34, etc.), and acidic oxides (such as γ-Al2O3, etc.).

[0037] The substantial features of the present invention are as follows:

[0038] In the current technology, the synthesis of dimethyl ether from syngas is carried out in one reactor, the carbonylation of dimethyl ether is carried out in one reactor, and the hydrogenation of methyl acetate is carried out in one reactor; and after each reactor, separation is required, and the process is complicated.

[0039] Aiming at the inhibitory effect of the intermediate product water on the existing molecular sieve catalyst for dimethyl ether carbonylation and the adverse effects on the subsequent process, the present technology proposes to design a new dimethyl ether synthesis catalyst. By using the impregnation method, the methanol synthesis catalyst component (CuZnAlO x ) and the methanol dehydration catalyst component (solid acid, such as molecular sieve, etc.) are highly coupled into a new type of catalyst, greatly shortening the spatial distance between the two catalytic components. At the same time, this synthesis method changes the microstructure of the methanol synthesis catalyst and improves its water-gas shift reaction performance. The obtained catalyst realizes in-situ chemical water removal by matching the water-gas shift reaction and the methanol dehydration reaction, basically eliminating the adverse effects of water on the subsequent dimethyl ether carbonylation and hydrogenation processes, avoiding the formation of by-product acetic acid and the corrosion problem of acetic acid on the subsequent hydrogenation system. At the same time, the catalyst forms a multifunctional catalytic system after being connected in series with the dimethyl ether carbonylation catalyst and the hydrogenation catalyst in sequence, simplifying the original series process into three steps of synthesizing dimethyl ether from syngas, synthesizing methyl acetate from dimethyl ether, and hydrogenating methyl acetate to ethanol (the process and related reactions are as Figure 2 shown), and finally realizing the efficient conversion of syngas directly to methyl acetate / ethanol. The specific reactions involved are as follows:

[0040] (1) 3CO + 3H2 → CH3OCH3 + CO2

[0041] (2) CH3OCH3 + CO → CH3COOCH3

[0042] (3) CH3COOCH3 + 2H2 → CH3OH + CH3CH2OH

[0043] Compared with the existing technology, the present invention has the following beneficial effects:

[0044] 1. The novel multifunctional catalytic system for directly preparing methyl acetate / ethanol from syngas prepared by the present invention has excellent catalytic performance. Under optimized conditions, the single-pass conversion rate of CO can be greater than 50%, the selectivity of methyl acetate in the organic phase product exceeds 90% (the highest in the current literature <85%), and the space-time yield can reach 0.53 g / g cat / h. After further connecting a hydrogenation catalyst in series, while ensuring that the CO conversion rate remains unchanged or slightly increases, the selectivity of ethanol in the obtained organic phase product can reach 60%, and it has good stability.

[0045] 2. The present invention proposes a new catalyst for preparing dimethyl ether from syngas and a tandem reaction path, which realizes a high degree of matching between the water-gas shift reaction and the methanol dehydration reaction microscopically, so that almost no water is generated in the front-end reaction of synthesizing dimethyl ether from syngas in this tandem system, avoiding the problems of reduced carbonylation activity and high selectivity of by-product acetic acid caused by competitive adsorption of water on the back-end dimethyl ether carbonylation catalyst.

[0046] 3. The present invention can effectively avoid the problems of equipment corrosion caused by acetic acid by-products, as well as the difficulties in the subsequent hydrogenation system conversion and the need to use noble metal catalysts.

[0047] 4. The multifunctional catalytic system proposed by the present invention has a relatively low price, a simple preparation method, and is easy to realize industrial scale-up production.

[0048] 5. The new process for directly preparing methyl acetate from syngas proposed by the present invention has a wide range of raw material sources, greatly simplifies the traditional process for synthesizing oxygen-containing compounds such as methyl acetate and ethanol from syngas, is easy to load the catalyst, the process is easy to operate and control, and has good industrial application prospects. 2+ 6. The novel multifunctional catalyst reported by the present invention has excellent methyl acetate activity at a relatively low H2 / CO molar ratio (i.e., 0.5) (the current literature reports all use H2 / CO = 2 or 1), and is suitable for the efficient utilization of syngas rich in CO, such as the utilization of coal-based, biomass-based syngas, and CO-rich industrial waste gas, etc.

[0049] BRIEF DESCRIPTION OF THE DRAWINGS BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 is the process route diagram for synthesizing ethanol from syngas in the current industry

[0051] Figure 2 is the process schematic diagram for directly preparing methyl acetate / ethanol from syngas proposed in this patent;

[0052] Figure 3 is the X-ray diffraction pattern of the CuZnAlO x / HZSM-5-IM(21) sample in Example 1.

[0053] Figure 4 The X-ray diffraction pattern of the metal oxide CuZnAlO obtained in Comparative Example 1 x sample.

[0054] Figure 5 The X-ray diffraction pattern of CuZnAlO x / HZSM-5-P(21) sample.

[0055] Figure 6 The X-ray diffraction pattern of HZSM-5(21) sample.

[0056] Figure 7 The scanning electron microscope image of CuZnAlO x / HZSM-5-IM(21) sample in Example 1.

[0057] Figure 8 The scanning electron microscope image of the metal oxide CuZnAlO x obtained in Comparative Example 1.

[0058] Figure 9 The scanning electron microscope image of CuZnAlO x / HZSM-5-P(21) sample in Comparative Example 1.

[0059] Figure 10 The scanning electron microscope image of HZSM-5(21) sample. Detailed implementation manners

[0060] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners. It should be noted that the following embodiments are illustrative and not restrictive, and the protection scope of the present invention cannot be limited by the following embodiments. The raw materials required in the following examples and comparative examples are all commercially available.

[0061] In this embodiment, a Rigaku MiniFlex 600 type powder X-ray diffractometer of Rigaku Corporation, Japan was used to analyze the crystal phase structure of the sample, and the diffraction source was CuKα The working voltage and working current were selected as 40 kV and 200 mA respectively, the scanning range was 5 - 90°, and the scanning speed was 8° / min.

[0062] In this embodiment, the morphology analysis of each sample was carried out using an Apreo SLoVac scanning electron microscope of Thermo Fisher Scientific.

[0063] The dimethyl ether carbonylation catalyst described in the present invention is a well-known material, specifically a hydrogen-type molecular sieve with an eight-membered ring pore structure and a hydrogen-type molecular sieve catalyst modified with a metal promoter; (Journal of Chemical Industry and Engineering (China) 2016, 67(1), 240-247, Journal of Energy Chemistry 2019, 36, 51-63, Journal of Chemical Industry and Engineering (China) 2021, 72, 3958-3967); but not limited thereto.

[0064] The hydrogenation catalyst described in the present invention is a well-known material, specifically a supported copper-based methyl acetate hydrogenation catalyst typically prepared by methods such as the impregnation method, deposition-precipitation method, and ammonia evaporation method. (Journal of Chemical Industry and Engineering (China) 2016, 67(1), 240-247, Industrial & Engineering Chemistry Research 2018, 57, 4526-4534, ACS Catalysis 2022, 12, 1315-1325); but not limited thereto.

[0065]

Example 1

[0066] Dissolve 7.25 g of copper nitrate trihydrate, 4.46 g of zinc nitrate hexahydrate, and 1.88 g of aluminum nitrate nonahydrate in 50 mL of deionized water to obtain a metal salt aqueous solution (wherein the total metal ion concentration is 1 mol / L and the molar ratio of copper:zinc:aluminum is 6:3:1); ultrasonically disperse 2 g of HZSM-5(21) molecular sieve in 250 mL of deionized water to obtain a suspension containing a solid acid catalyst with a concentration of 8 g / L; dissolve sodium carbonate solid in an appropriate amount of deionized water to prepare a 1 mol / L alkali solution.

[0067] Drop the above metal salt aqueous solution and alkali solution into the suspension containing the solid acid catalyst simultaneously under stirring at a volume ratio of 5:8 until the metal salt aqueous solution is consumed (wherein the mass ratio is solid acid catalyst:CuZnAlO x = 1:2), and then stir and age at room temperature for 3 hours; then filter and wash the suspension to neutrality, dry at 100 °C for 12 hours, and calcine at 350 °C for 5 hours to finally obtain the required syngas-to-dimethyl ether catalyst CuZnAlO x / HZSM-5-IM(21).

[0068] The prepared CuZnAlO x / HZSM-5-IM(21) sample's XRD pattern is as shown in the appendix Figure 3 and has typical diffraction peaks of HZSM-5 molecular sieve and is well-crystallized; at the same time, the corresponding CuO characteristic diffraction peaks are observed. In addition, the sample morphology is as shown in the appendix Figure 7 and it is observed that the metal composite oxide CuZnAlO x is highly dispersed on the surface of the HZSM-5 molecular sieve.

[0069] The hydrogen form MOR molecular sieve (molar ratio of SiO2 to Al2O3 is 24); the obtained HMOR molecular sieve is pretreated with pyridine vapor for 3 hours to obtain the required dimethyl ether carbonylation catalyst Py-HMOR.

[0070] Take 0.5 g of the syngas-to-dimethyl ether catalyst CuZnAlO x / HZSM-5-IM(21) sample and 0.5 g of the dimethyl ether carbonylation catalyst Py-HMOR sample after pressing and screening (40 - 60 mesh), and load them in series through a double-bed layer (reactor inner diameter 8 mm, tube length 60 cm). Among them, the dimethyl ether carbonylation catalyst Py-HMOR is placed in the lower layer of the fixed-bed reactor. At 260 °C, 2 MPa, the raw material gases H2 and CO (molar ratio of H2 to CO is 0.5, total flow rate 50 mL / min) are introduced into the reactor from the top of the reactor and pass through the syngas-to-dimethyl ether catalyst and the dimethyl ether carbonylation catalyst in sequence, and finally methyl acetate with a selectivity of 86.4% and a yield of 0.243 g / g cat / h is obtained.

[0071] Before the reaction, the catalyst is reduced in a 10% H2 / 90% N2 atmosphere at 260 °C for 3 hours. The results of the on-line gas chromatography analysis of the reaction tail gas with heat preservation are processed according to the following formulas:

[0072] (1) CO conversion rate = (moles of inlet CO - moles of outlet CO) / moles of inlet CO × 100%;

[0073] (2) CO2 selectivity = moles of outlet CO2 / (moles of inlet CO - moles of outlet CO) × 100%;

[0074] (3) Selectivity of product C i (excluding CO2) = (moles of outlet product C i × number of carbon atoms in product C i ) / ∑(moles of outlet product C i × number of carbon atoms in product molecule C i ) × 100%;

[0075] (4) Space-time yield (STY) of product C i = inlet CO molar flow rate × CO conversion rate × (1 - CO2 selectivity) × selectivity of product C i (excluding CO2) × molecular weight of product C i / (number of carbon atoms in product C i × total mass of the series-connected catalysts)

[0076] Comparative Example 1

[0077] Dissolve 7.25 g of copper nitrate trihydrate, 4.46 g of zinc nitrate hexahydrate, and 1.88 g of aluminum nitrate nonahydrate in 50 mL of deionized water to obtain a metal salt aqueous solution; dissolve sodium carbonate solid in an appropriate amount of deionized water to prepare a 1 mol / L alkali solution.

[0078] Drop the above metal salt aqueous solution and the alkali solution into 250 mL of deionized water simultaneously under stirring according to a volume ratio of 5:8 until the metal salt aqueous solution is consumed, and then stir and age at room temperature for 3 hours; then filter and wash the suspension until it is neutral, dry it at 100 °C for 12 hours, and calcine it at 350 °C for 5 hours to finally obtain the required metal oxide CuZnAlO x 。

[0079] The prepared metal oxide CuZnAlO x The XRD pattern of the sample is as attached Figure 4 shown; the morphology of the sample is as attached Figure 8 shown.

[0080] Mix the above metal oxide CuZnAlO x with 2 g of HZSM-5(21) molecular sieve by powder mixing, and then grind it thoroughly in an agate mortar for 10 minutes to finally obtain the required comparative sample of the catalyst for synthesizing dimethyl ether from syngas CuZnAlO x / HZSM-5-P(21).

[0081] The prepared comparative sample CuZnAlO x The XRD pattern of the / HZSM-5-P(21) sample is as attached Figure 5 shown; the morphology of the sample is as attached Figure 9 shown.

[0082] In addition, the XRD pattern of the used molecular sieve HZSM-5(21) sample is as attached Figure 6 shown; the morphology is as attached Figure 10 shown.

[0083] Take 0.5 g of the sieved comparative sample of the catalyst for synthesizing dimethyl ether from syngas CuZnAlO x / HZSM-5-P(21) sample and 0.5 g of the sieved sample of the catalyst for dimethyl ether carbonylation Py-HMOR, and connect them in series through a double-bed layer, where the catalyst for dimethyl ether carbonylation Py-HMOR is placed in the lower layer of the fixed-bed reactor; other evaluation conditions and data processing are exactly the same as those in Example 1.

[0084] The reaction performance of the obtained multifunctional catalyst for the tandem one-step synthesis of methyl acetate from syngas is shown in Table 1. The data listed in the table are the average performance within 5 - 11 h of the reaction. The reaction can reach a steady state within 4 - 5 h, and the fluctuation error of CO conversion and methyl acetate selectivity within the subsequent 72 h of the reaction is within ±3%, indicating that the catalyst has good stability during the operation time. Other products include a small amount of methanol, acetic acid, acetone, and hydrogen-carbon species. The subsequent tables are the same as this one.

[0085] Table 1 Catalytic performance of the multifunctional catalytic system for the tandem one-step synthesis of methyl acetate from syngas

[0086]

[0087] From the activity, it can be seen that compared with Comparative Example 1, the CO conversion of the raw materials of Example 1 of the novel multifunctional catalyst reported in the present invention has been greatly improved, the space-time yield of methyl acetate has increased by 80 times, and the acetic acid selectivity has been greatly reduced, only being 8.1%.

[0088]

Examples 2 - 3

[0089] Under the condition that other conditions are exactly the same as those in Example 1, only the molar ratio of H2 / CO in the raw material gas during the catalyst evaluation process is changed to 1 (Example 2) and 2 (Example 3).

[0090] The influence of the molar ratio of H2 / CO in the raw material gas on the reaction performance of the obtained multifunctional catalyst for the tandem one-step synthesis of methyl acetate from syngas is shown in Table 2.

[0091] Table 2 Influence of the molar ratio of H2 / CO in the raw material gas on the reaction performance of the tandem one-step synthesis of methyl acetate from syngas

[0092]

[0093] From the activity, it can be seen that the novel multifunctional catalyst reported in the present invention can obtain excellent methyl acetate yields at lower H2 / CO molar ratios, and is suitable for the efficient utilization of syngas rich in CO, such as the utilization of coal-based, biomass-based syngas, and CO-rich industrial waste gas, etc.

[0094]

Examples 4 - 6

[0095] Under the condition that other conditions are exactly the same as those in Example 1, the reaction pressure during the catalyst evaluation process is changed to 4 MPa and the mass of the dimethyl ether carbonylation catalyst Py-HMOR is 0.5 g (Example 4), 0.75 g (Example 5), and 1.0 g (Example 6).

[0096] The influence of the catalyst mass ratio on the reaction performance of the obtained multifunctional catalyst for the tandem one-step synthesis of methyl acetate from syngas is shown in Table 3.

[0097] Table 3 Influence of mass ratio of different functional components on the reaction performance of one-step synthesis of methyl acetate from syngas in series

[0098]

[0099] It can be seen from the activity that there is an optimal ratio between the syngas-to-dimethyl ether catalyst and the dimethyl ether carbonylation catalyst. With the increase in the mass of the dimethyl ether carbonylation catalyst, the CO conversion rate of this multifunctional catalyst system gradually increases, and the methyl acetate yield also increases. And when the mass ratio of the syngas conversion-to-dimethyl ether catalyst to the dimethyl ether carbonylation catalyst is 0.5 g:0.75 g, multiple reactions involved in this multifunctional catalyst can achieve a high degree of kinetic matching. Syngas can well pass through the new path of dimethyl ether coupling and obtain excellent methyl acetate selectivity and space-time yield through a series of relay reactions.

[0100]

Examples 7 - 9

[0101] Under the condition that other conditions are exactly the same as those in Example 5, change the reaction pressure during the catalyst evaluation process to 2 MPa (Example 7), 3 MPa (Example 8), and 4.5 MPa (Example 9). The reaction results are shown in Table 4.

[0102] Table 4 Influence of reaction pressure on the reaction performance of one-step synthesis of methyl acetate from syngas in series

[0103]

[0104] It can be seen from the activity that with the increase in the reaction pressure, the space-time yield of methyl acetate of this multifunctional catalyst system gradually increases. At the same time, with the increase in the reaction pressure, no obvious change in the selectivity of each product is observed, indicating that the pressure operation space of the reaction is relatively wide.

[0105]

Examples 10 - 11

[0106] Under the condition that other conditions are exactly the same as those in Example 5, only replace the dimethyl ether carbonylation catalyst Py-HMOR with hydrogen-type FER (Example 10, SiO2 / Al2O3 = 28) or hydrogen-type SSZ-13 (Example 11, SiO2 / Al2O3 = 34). Without pre-adsorption treatment with pyridine, react for 11 h, and the results are shown in Table 5.

[0107] Table 5 Influence of the type of dimethyl ether carbonylation catalyst on the reaction performance of one-step synthesis of methyl acetate from syngas in series

[0108]

[0109] It can be seen from the activity that when the molecular sieve used in the dimethyl ether carbonylation catalyst is Py-HMOR, the space-time yield of methyl acetate of this multifunctional catalyst system is the highest.

[0110]

Example 12

[0111] The preparation method of the hydrogenation catalyst Cu / SiO2 adopts the ammonia evaporation homogeneous precipitation deposition method: Weigh 15.2 g of copper nitrate trihydrate and dissolve it in 100 mL of deionized water. Then add 50 mL of ammonia water (25 wt%) to form a copper ammonia solution, and stir evenly. Then, a certain amount of silica sol (30 wt%) is added dropwise at a certain rate and stirred and aged for 24 hours. The blue suspension is evaporated of ammonia at 80 °C until the pH drops to between 6 and 7, and the ammonia evaporation ends. After filtration, washing, drying at 80 °C for 12 hours, and calcining at 400 °C for 4 hours, the required hydrogenation catalyst Cu / SiO2 is obtained. (The Cu loading is 20 wt.%)

[0112] Take 0.5 g of the syngas-to-dimethyl ether catalyst CuZnAlO x / HZSM-5-IM(21) sample, 0.75 g of the dimethyl ether carbonylation catalyst Py-HMOR sample after tabletting and screening (40 - 60 mesh), and 0.5 g of the hydrogenation catalyst Cu / SiO2 sample after screening (40 - 60 mesh), and load them in series through three beds (the inner diameter of the reactor is 8 mm, and the tube length is 60 cm). Among them, the syngas-to-dimethyl ether catalyst is placed in the upper layer of the fixed-bed reactor, the dimethyl ether carbonylation catalyst is placed in the middle layer of the fixed-bed reactor, and the hydrogenation catalyst is placed in the lower layer of the fixed-bed reactor. At 260 °C, 4 MPa, the raw material gases H2 and CO (the molar ratio of H2 and CO is 0.5, and the total flow rate is 50 mL / min) are introduced into the reactor from the top of the reactor and sequentially pass through the syngas-to-dimethyl ether catalyst, the dimethyl ether carbonylation catalyst, and the hydrogenation catalyst, and finally ethanol with a selectivity of 60% and a yield of 0.228 g / g cat / h is obtained.

[0113] The reaction performance is shown in Table 6.

[0114] Table 6 Performance of the one-step tandem synthesis of ethanol from syngas

[0115]

[0116] It can be seen from the reaction data that this multifunctional catalyst has excellent performance in the one-step tandem synthesis of ethanol from syngas.

[0117] Matters not covered by this invention are well-known technologies.

Claims

1. A multifunctional tandem catalytic process for directly preparing methyl acetate / ethanol from syngas, characterized by adopting one of the following two methods: Method 1 includes the following steps: Feed the raw material gases H2 and CO into a fixed-bed reactor successively equipped with a syngas-to-dimethyl ether catalyst and a dimethyl ether carbonylation catalyst to obtain methyl acetate; Among them, The reaction temperature is 200 - 350 °C, the reaction pressure is 1 - 6 MPa, the molar ratio of H2 / CO in the raw material gas is 0.2 - 4; the total reaction space velocity is 500 - 6000 mL / g cat / h; in the bed layer, by mass ratio, the syngas-to-dimethyl ether catalyst in the upper layer: the dimethyl ether carbonylation catalyst in the lower layer = 1:(0.5 - 3); Or, Method 2 includes the following steps: Feed the raw material gases H2 and CO into a fixed-bed reactor successively equipped with a syngas-to-dimethyl ether catalyst, a dimethyl ether carbonylation catalyst and a hydrogenation catalyst to obtain ethanol; Among them, the reaction temperature is 200 to 350 °C, the reaction pressure is 1 to 6 MPa, the molar ratio of H2 / CO in the raw material gas is 0.2 to 4; the total reaction space velocity is 500 to 6000 mL / g cat / h; in the bed layer, the mass ratio is that the syngas-to-dimethyl ether catalyst in the upper layer: the dimethyl ether carbonylation catalyst in the middle layer: the hydrogenation catalyst in the lower layer = 1:(0.5 to 3):(0.5 to 2); The dimethyl ether carbonylation catalyst is a hydrogen-type molecular sieve catalyst or a hydrogen-type molecular sieve catalyst modified with a metal promoter; The hydrogenation catalyst is a supported copper-based methyl acetate hydrogenation catalyst prepared by the impregnation method, the deposition-precipitation method or the ammonia evaporation method; The preparation method of the syngas-to-dimethyl ether catalyst includes the following steps: (1) Take a copper source, a zinc source, an aluminum source, a promoter precursor and water, stir and mix them to obtain a metal salt aqueous solution; Among them, the molar ratio is copper:zinc = 0.5 - 5:1, (copper + zinc):aluminum = 2 - 15:1; The total molar concentration of copper, zinc and aluminum in the metal salt aqueous solution is 0.5 - 2 mol / L; The promoter precursor is one or more of nitrates, sulfates, acetates, phosphates, chlorides of promoter active elements; the promoter active elements are one or more of silicon, chromium, iron, cobalt, nickel, gallium, zirconium, molybdenum, cerium; The mass of the promoter active element is 0.1 - 5 wt.% of the total mass of the syngas-to-dimethyl ether catalyst; the syngas-to-dimethyl ether catalyst includes metal oxides, solid acids and promoter active elements; (2) Take an alkali source and water, stir and mix them to obtain an alkali solution with a molar concentration of 0.5 - 5 mol / L; (3) Disperse the solid acid catalyst in water to obtain a suspension containing the solid acid catalyst; the concentration is 1 - 20 g / L; (4) Drop the solutions obtained in steps (1) and (2) into the suspension obtained in step (3) simultaneously according to a volume ratio of (0.5 - 2):1 under stirring to obtain a new suspension; The mass ratio is solid acid catalyst:metal oxide = 1:0.5 - 5; (5) Stir and age the suspension obtained in step (4) at room temperature to 95 °C for 0 - 24 hours, then filter and wash it until it is close to neutral, and dry it at 80 - 150 °C for 1 - 24 hours and calcine it at 250 - 500 °C for 1 - 24 hours to obtain the required syngas-to-dimethyl ether catalyst.

2. The multifunctional tandem catalytic process for directly preparing methyl acetate / ethanol from syngas according to claim 1, characterized in that, The hydrogen-type molecular sieve catalyst is MOR, FER or SSZ-13; Among them, the silicon-aluminum ratio is: in MOR, (SiO2 / Al2O3 = 5 - 30), in FER (SiO2 / Al2O3 = 5 - 30), in SSZ-13 (SiO2 / Al2O3 = 5 - 40); In the metal promoter-modified hydrogen-type molecular sieve catalyst, it also includes a promoter metal element; the promoter metal element is one or more of cerium, tin, gallium, iron, copper, nickel, silver, cobalt, zinc, and the loading is 0.5 - 10 wt.%; 3. The multifunctional tandem catalytic process for directly preparing methyl acetate / ethanol from syngas according to claim 1, characterized in that, In the supported copper-based methyl acetate hydrogenation catalyst, the loading of the active metal Cu is 5 - 40 wt.%; The carrier is one or more of SiO2, CeO2, ZnO, ZrO2, and Al2O3; The promoter elements are one or more of molybdenum, cobalt, zinc, manganese, iron, and lanthanum, and the loading amount is 0.05 - 3 wt.%.

4. The multifunctional tandem catalytic process for directly preparing methyl acetate / ethanol from syngas according to claim 1, characterized in that, In step (1), the copper source is one or more of copper nitrate, copper sulfate, and copper acetate; the zinc source is one or more of zinc nitrate, zinc sulfate, and zinc acetate; the aluminum source is one or more of aluminum nitrate, aluminum sulfate, and sodium metaaluminate.

5. The multifunctional tandem catalytic process for directly preparing methyl acetate / ethanol from syngas as claimed in claim 1, wherein In step (2), the base source is one or more of sodium carbonate, sodium bicarbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, and ammonia water.

6. The multifunctional tandem catalytic process for directly preparing methyl acetate / ethanol from syngas according to claim 1, characterized in that, In step (3), the solid acid catalyst is one of aluminosilicate zeolite, silicoaluminophosphate zeolite, or acidic oxide.

7. The multifunctional tandem catalytic process for directly preparing methyl acetate / ethanol from syngas according to claim 6, characterized in that, The aluminosilicate zeolite is HZSM-5, H-β, HY, or H-MOR; the silicoaluminophosphate zeolite is SAPO-11 or SAPO-34; the acidic oxide is γ-Al2O3.

8. A preparation method of a catalyst for synthesizing dimethyl ether from syngas, characterized in that, It includes the following steps: (1) Take the copper source, zinc source, aluminum source, promoter precursor, and water, stir and mix them to obtain a metal salt aqueous solution; Among them, the molar ratio is copper:zinc = 0.5 - 5:1, (copper + zinc):aluminum = 2 - 15:1; The total molar concentration of copper, zinc, and aluminum in the metal salt aqueous solution is 0.5 - 2 mol / L; The promoter precursor is one or more of nitrates, sulfates, acetates, phosphates, and chlorides of promoter active elements; the promoter active elements are one or more of silicon, chromium, iron, cobalt, nickel, gallium, zirconium, molybdenum, and cerium; The mass of the promoter active element is 0.1 - 5 wt.% of the total mass of the syngas-to-dimethyl ether catalyst; the syngas-to-dimethyl ether catalyst includes metal oxides, solid acids, and promoter active elements. (2) Take the base source and water, stir and mix them to obtain a base solution with a molar concentration of 0.5 - 5 mol / L; (3) Disperse the solid acid catalyst in water to obtain a suspension containing the solid acid catalyst; the concentration is 1 - 20 g / L; (4) Drop the solutions obtained in step (1) and step (2) into the suspension obtained in step (3) simultaneously with a volume ratio of (0.5 - 2):1 under stirring to obtain a new suspension; The mass ratio is solid acid catalyst:metal oxide = 1:0.5 - 5; (5) Stir and age the suspension obtained in step (4) at room temperature to 95 °C for 0 - 24 hours, then filter and wash it until it is close to neutral, and dry it at 80 - 150 °C for 1 - 24 hours, and calcine it at 250 - 500 °C for 1 - 24 hours to obtain the required syngas-to-dimethyl ether catalyst; In step (1), the copper source is one or more of copper nitrate, copper sulfate, and copper acetate; the zinc source is one or more of zinc nitrate, zinc sulfate, and zinc acetate; the aluminum source is one or more of aluminum nitrate, aluminum sulfate, and sodium metaaluminate; In step (2), the base source is one or more of sodium carbonate, sodium bicarbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, and ammonia water; The solid acid catalyst described in step (3) is one of silicoaluminate molecular sieve, silicoaluminophosphate molecular sieve or acidic oxide.

9. The preparation method of the syngas-to-dimethyl ether catalyst according to claim 8, characterized in that, The silicoaluminate molecular sieve is HZSM-5, H-β, HY or H-MOR; the silicoaluminophosphate molecular sieve is SAPO-11 or SAPO-34; the acidic oxide is γ-Al2O3.

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