A method for catalytically oxidizing furfural to produce furoic acid with high selectivity

Abstract

The invention discloses a method for preparing furoic acid by catalytic oxidation of furfural with high selectivity. The method comprises the following steps: mixing furfural, a solvent, a transition metal catalyst and an alkaline co-catalyst, reacting for more than 10 minutes at a reaction temperature higher than 45 DEG C in the presence of oxygen to obtain furoic acid; the alkaline co-catalyst is selected from at least one of MgO, CaO and SrO; the method uses a transition metal as a main catalyst and an alkaline oxide as a co-catalyst, and has the advantages of mild reaction conditions, high furoic acid selectivity, good catalyst stability, simple reaction process and the like.

Description

Technical Field

[0001] The present invention relates to a method for realizing high-selective catalytic oxidation of furfural to prepare furoic acid and MO prepared by a transition metal isovolumetric impregnation method x / Application of a supported catalyst in catalyzing the oxidation of furfural to produce furoic acid, specifically relating to reaction conditions for catalyzing the oxidation of furfural to produce furoic acid, a catalyst preparation method and a method of use. Background Art

[0002] Furfural is a renewable chemical raw material derived from biomass. Its oxidation to furoic acid has broad application prospects in food, cosmetics, medicine and renewable polymer industries. It is an important raw material for synthesizing plasticizers and various drugs. [Li Xinglong, Synthesis of furoic acid from furfural oxidation, Progress in Chemistry, 2022, 34, 1264-1273] In addition, furoic acid can also react with carbon dioxide to synthesize a new bio-based material monomer 2,5-furandicarboxylic acid, and then synthesize the bio-based furan material polyethylene 2,5-furandicarboxylate. [F. Drault, Y. Snoussi, Recent Advances in Carboxylation of Furoic Acid into 2,5-Furandicarboxylic Acid: Pathways towards Bio-Based Polymers, Chem Sus Chem, 2020, 13 (19): 5164]

[0003] At present, there are three main process routes for preparing furoic acid from furfural: Cannizarro disproportionation method, equivalent oxidant oxidation method, and catalytic oxidation method. The Cannizarro method converts furfural into furoic acid and furfuryl alcohol in the presence of sodium hydroxide as a strong alkaline catalyst. The maximum yield of this reaction is 50% (forming an equimolar amount of furfuryl alcohol), and the raw material utilization rate is poor, which is not suitable for large-scale industrial production. [F. Chacón-Huete, C. Messina, Solvent-free mechanical oxidation and reduction of biomass-derived 5-hydroxymethyl furfural, Green Chem., 2018, 20, 5261-5265] The equivalent oxidant oxidation method mainly uses tert-butyl peroxide, potassium dichromate, hydrogen peroxide, etc. as oxidants. This method has problems such as low selectivity, more three wastes, and potential safety hazards. [Ning Liangmin, Liao Shengyun, Catalytic conversion of biomass platform compound furfural, Petrochemicals, 2017, 46(1), 130-136] Compared with the above two methods, the catalytic oxidation method has relatively mild conditions, less environmental pollution, and is more suitable for industrial production. At present, furoic acid is usually prepared using metal oxides as catalysts and strong bases as auxiliary agents. In industrial production, copper oxide is used as a catalyst and NaOH is used as an auxiliary agent, and the furoic acid selectivity does not exceed 60%. [Zhang Chengming, Xu Xianlun, Preparation of nano-CuO and its catalytic oxidation performance of furfural, Industrial Catalysis, 2010, 18(11), 69-72] In laboratory studies, Mark et al. used AuPd / Mg(OH) 2 The controlled catalytic oxidation of furfural to furoic acid using AuPd / Mg(OH) was carried out for 4 h in the presence of 0.6 mol / L NaOH. 2 ,Catal.Sci.Technol.,2017,7,5284-5293]Xin et al., using Ni / Ni-N / CN as catalyst, reacting at 110℃ for 3h in the presence of NaOH, the yield of furoic acid was 80%. [Y.Xin,M.Zuo,Insight into the catalytic mechanism of core–shell structuredNi / Ni-N / CN catalyst towards the oxidation of furfural to furancarboxylicacid,

[0004] Fuel, 2022, 317] Therefore, developing a highly selective catalyst for the oxidation of furfural to produce furoic acid has important application value. Summary of the invention

[0005] The invention provides a method for preparing furoic acid by catalytic oxidation of furfural with high selectivity.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for preparing furoic acid by highly selective catalytic oxidation of furfural comprises the following steps: mixing furfural, a solvent, a transition metal catalyst and an alkaline co-catalyst, reacting at a temperature higher than 50° C. for more than 10 minutes in the presence of oxygen to obtain furoic acid.

[0008] Furthermore, in the above technical scheme, the optimized reaction temperature is 50-180°C, the reaction time is 0.5-12h, the oxygen pressure is 0.1-5.0MPa, the solvent is water, the furfural concentration is 0.02-5mol / L, the amount of transition metal catalyst is 0.1-10 times the mass of the reactants, and it contains at least one of the alkaline promoters MgO, CaO, and SrO, and the molar ratio of the alkaline promoter to furfural is 0.1-10.

[0009] Furthermore, in the above technical scheme, the more optimized reaction temperature is 60-140°C, the reaction time is 0.8-8h, the oxygen pressure is 0.5-3.0MPa, the solvent is water, the furfural concentration is 0.04-3mol / L, the amount of transition metal catalyst is 0.2-3 times the mass of the reactants, and the molar ratio of the alkaline co-catalyst to furfural is 0.2-6.

[0010] Furthermore, in the above technical solution, the transition metal catalyst is of formula MO x / carrier, wherein M is one or more of the transition metal elements Co, Rh, Ir, Ni, Pd, Pt, Ru, Cu, Au, and Ag, and x is a value determined by the oxygen in the above-mentioned metal oxides; the total loading amount of the transition metal element M is 0.1-50wt%, and the carrier is one or more of zirconium dioxide, aluminum oxide, activated carbon, carbon nanotubes, and graphene oxide.

[0011] Furthermore, in the above technical solution, a more preferred solution is that the loading amount of the transition metal element on the transition metal catalyst in the catalyst is 0.5-30wt%.

[0012] Further, in the above technical solution, the transition metal catalyst is prepared according to the following method: a soluble salt of the transition metal is dissolved in water and then impregnated on a carrier, dried at 50-140°C for more than 6 hours, and then calcined at 250-550°C for a calcination time of not less than 0.5 hours to obtain a catalyst MO x / vector.

[0013] Furthermore, in the above technical solution, a more optimal solution is that the transition metal catalyst is prepared according to the following method: the impregnation time is 2-12 hours, the drying temperature is 60-130°C, the calcination temperature is 350-500°C, and the calcination time is 2-6 hours.

[0014] Furthermore, in the above technical scheme, a more preferred scheme is that the transition metal catalyst is prepared according to the following method: the soluble salt of the active component is one or more of cobalt nitrate, rhodium nitrate, iridium nitrate, nickel nitrate, palladium nitrate, platinum chloride, ruthenium chloride, copper nitrate, tetrachloroauric acid and silver nitrate.

[0015] The present invention has the following advantages:

[0016] (1) The reaction conditions are mild, and the use of alkaline co-catalysts such as calcium oxide instead of strong bases such as sodium hydroxide is more environmentally friendly.

[0017] (2) The reaction selectivity is high, with a furfural conversion rate of 100% and a furoic acid selectivity of up to 97.2%.

[0018] (3) The catalyst preparation process is simple and easy to scale up for industrial synthesis.

[0019] (4) The catalyst has good stability and still has a selectivity of more than 90% for furoic acid after multiple cycles.

[0020] Taking the above factors into consideration, the method for preparing furoic acid from furfural with high selectivity of the present invention has significant technical advancement and good application prospects.

[0021] The following is further detailed description through specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 1% AgO x / ZrO 2 Catalyst cyclic stability investigation results. DETAILED DESCRIPTION

[0023] Example 1

[0024] Preparation of different transition metal catalysts MO by impregnation method x / ZrO 2 :

[0025] Step 1, respectively dissolving soluble transition metal salts of cobalt nitrate, iron nitrate, palladium nitrate, ruthenium chloride, copper nitrate, tetrachloroauric acid and silver nitrate in water, and impregnating them with zirconium dioxide in equal volumes, with a transition metal loading of 1%, and impregnating for 8 hours.

[0026] Step 2: Dry the sample in step 1 at 60°C overnight.

[0027] Step 3: After calcining the sample in step 2 at 450°C in air for 4 h, Co 3 O 4 / ZrO 2 , Fe 2 O 3 / ZrO 2 , PdO x / ZrO 2 , RuO x / ZrO 2 , CuO / ZrO 2 , AuO x / ZrO 2 and AgO x / ZrO 2 catalyst.

[0028] Example 2

[0029] Preparation of AgO on different supports by impregnation method x / Carrier Catalyst:

[0030] Step 1: A soluble salt of Ag is dissolved in water and impregnated with an equal volume of zirconium dioxide, aluminum oxide, titanium dioxide, activated carbon and graphene oxide, with a metal loading of 1%, and the impregnation is carried out for 8 hours.

[0031] Step 2: Dry the sample in step 1 at 120°C overnight.

[0032] Step 3: calcining the carbon-based carrier sample in step 2 at 350°C in air for 4 hours to obtain AgO x / AC and AgO x The samples other than the carbon-based support in step 2 were calcined in air at 450 °C for 4 h to obtain AgO x / ZrO 2 、AgO x / Al 2 O 3 and AgO x / TiO 2 catalyst.

[0033] Example 3

[0034] Preparation of X% AgO with different Ag loading by impregnation method x / ZrO2 catalyst:

[0035] Step 1, a soluble salt of Ag is dissolved in water and impregnated with an equal volume of a zirconium dioxide carrier. The metal loading amount is selected from 0.1%, 0.5%, 1%, 2%, 5%, and 10%, and the impregnation is carried out for 8 hours.

[0036] Step 2: Dry the sample in step 1 at 60°C overnight.

[0037] Step 3: After calcining the sample in step 2 at 450°C in air for 4 h, catalysts with different loadings were obtained. x / ZrO 2 , 0.5%AgO x / ZrO 2 , 1%AgO x / ZrO 2 , 2%AgO x / ZrO 2 , 5%AgO x / ZrO 2 , 10%AgO x / ZrO 2 .

[0038] Example 4

[0039] Catalytic oxidation of furfural to prepare furoic acid catalyst evaluation process: Furfural catalytic oxidation reaction was carried out in a reactor. 20mL of 0.05mol / L furfural aqueous solution, transition metal catalyst prepared in the above case and alkaline co-catalyst calcium oxide were added to the reactor. Among them, the mass ratio of transition metal catalyst to furfural was 1:1, and the molar ratio of alkaline co-catalyst to furfural was 2:1. Oxygen was filled into the reactor at 1.0MPa and reacted at 100℃ for 2h.

[0040] The reaction conversion and selectivity are calculated based on the molar amounts of raw materials and products:

[0041] Furfural conversion rate (%) = (n 反应前的糠醛 -n 反应后剩余糠醛 ) / n 反应前的糠醛 *100%

[0042] Furoic acid selectivity (%) = n 产物中糠酸 / (n 反应前的糠醛 -n 反应后剩余糠醛 )*100%

[0043] Example 5

[0044] MO loaded with different transition metals in Example 1 x / ZrO 2 Catalyst performance evaluation: reaction conditions were the same as in Example 4.

[0045]

[0046] It can be seen from the reaction results that the selectivity of the catalyst system used in the present invention in the furfural oxidation to furoic acid reaction is higher than 75%. x / ZrO 2 The catalyst has the best effect, with furfural selectivity as high as 97.2%. x / ZrO 2 , Fe 2 O 3 / ZrO 2 The selectivities over the catalyst were only 5.6% and 46.8%.

[0047] Example 6

[0048] AgO on different carriers in Example 2 x / Carrier catalyst performance evaluation, the reaction conditions are the same as Example 4.

[0049]

[0050] It can be seen from the reaction results that ZrO 2 、Al 2 O 3 , AC and GO as carriers are beneficial to the conversion of furfural to furoic acid. 2 The best effect is when used as a carrier. 2 When used as a carrier, the effect is poor.

[0051] Example 7

[0052] Different loading amounts of X% AgO in Example 3 x / ZrO 2 Catalyst performance evaluation: reaction conditions were the same as in Example 4.

[0053]

[0054] From the reaction results, it can be seen that when the Ag loading is 1-5%, it has relatively good catalytic performance, and the best performance is achieved when the loading is 2%.

[0055] Example 8

[0056] The catalytic conversion performance of furfural was evaluated at different reaction times. The reaction time was 0.5-12h, and the transition metal catalyst was 1% AgO x / ZrO 2 Catalyst. Other reaction conditions are the same as in Example 4.

[0057]

[0058] From the reaction results, it can be seen that the reaction conditions of 0.5-6h have relatively good furoic acid selectivity, and the furoic acid selectivity reaches the highest when the reaction time is 2h. In addition, furoic acid is stably present in the method of the present invention, and no obvious further reaction of furoic acid occurs when the reaction time is extended to 12 hours.

[0059] Example 9

[0060] The catalytic conversion performance of furfural was evaluated at different reaction temperatures. The transition metal catalyst was 1% AgO x / ZrO 2 Catalyst. Except for the reaction temperature, other reaction conditions are the same as those in Example 4.

[0061]

[0062] As can be seen from the table, the method provided by the present invention can generate furoic acid with high selectivity at the above-mentioned reaction temperatures. Among them, when the reaction temperature is around 100°C, the furoic acid selectivity is the highest.

[0063] Example 10

[0064] The catalytic conversion performance of furfural was evaluated under different oxygen pressures. The oxygen pressure was 0.1-5.0Mpa, and the transition metal catalyst was 1% AgO x / ZrO 2 The other reaction conditions are the same as those in Example 4.

[0065]

[0066]

[0067] As can be seen from the table, the present invention can obtain very high furoic acid selectivity under the above-investigated oxygen pressure. Among them, when the oxygen pressure is near 1.0 MPa, the furoic acid selectivity is the highest.

[0068] Embodiment 11

[0069] Evaluation of catalytic conversion performance at different furfural concentrations. Furfural concentration was 0.02-1.0 mol / L, transition metal catalyst was 1% AgO x / ZrO 2 Catalyst. Other reaction conditions are the same as in Example 4.

[0070]

[0071] It can be seen from the table that the present invention can obtain higher furoic acid selectivity under the above-mentioned furfural concentrations.

[0072] Example 12

[0073] Evaluation of the catalytic conversion performance of furfural under different molar ratios of alkaline co-catalyst to furfural. The molar ratio of alkaline co-catalyst to furfural is 0:1-10:1, and the transition metal catalyst is 1% AgO x / ZrO 2 Catalyst. Other reaction conditions are the same as in Example 4.

[0074]

[0075] As can be seen from the table, the presence of alkaline promoter is crucial for catalyzing furfural to prepare furoic acid with high selectivity. When the molar ratio of alkaline promoter to furfural is 0.5:1-5:1, the selectivity of furoic acid is high, and the selectivity of furoic acid reaches the highest when the molar ratio is 2:1. Without the alkaline promoter CaO, the selectivity of furoic acid is only 7.4%.

[0076] Embodiment 13

[0077] The catalytic conversion performance of furfural was evaluated under different alkaline co-catalysts. The transition metal catalyst was 1% AgO x / ZrO 2 Catalyst. Other reaction conditions are the same as in Example 4.

[0078]

[0079] It can be seen from the table that when the alkaline co-catalyst of the present invention is used, the selectivity of furoic acid is significantly better than that of NaOH and NaHCO 3 result.

[0080] Embodiment 14

[0081] The catalyst 1% AgO x / ZrO 2 The first reaction conditions were the same as in Example 4. After the reaction, 1% AgO x / ZrO 2 The catalyst was separated from the filtrate by filtration, washed with 1% dilute nitric acid, and then put back into the reactor to react again according to the conditions of Example 4. This process was repeated several times to evaluate the catalyst cycle stability. Figure 1 shown.

[0082] from Figure 1 It can be seen that after four cycles, 1% AgO x / ZrO 2 The catalyst has stable performance, still maintains high catalytic activity, and the furoic acid selectivity is maintained at more than 90%.

[0083] In summary, the present invention provides a method for producing furoic acid by highly selective catalytic oxidation of furfural, which has the advantages of high furoic acid selectivity, good catalyst stability, simple reaction process, etc.

Claims

1. A method for producing furoic acid by high-selectivity catalytic oxidation of furfural, characterized in that: The method comprises the following steps: mixing furfural, a solvent, a transition metal catalyst and an alkaline co-catalyst, reacting for more than 10 minutes at a reaction temperature higher than 45° C. in the presence of oxygen to obtain furoic acid; the alkaline co-catalyst is selected from at least one of MgO, CaO and SrO; Transition metal catalysts with formula MO x / carrier, wherein M is one or more of the transition metal elements Co, Rh, Ir, Ni, Pd, Pt, Ru, Cu, Au, and Ag, and x is a value determined by the oxygen in the above metal oxides; the total loading of the transition metal element M is 0.5-30wt%, and the carrier is one or more of zirconium dioxide, aluminum oxide, activated carbon, carbon nanotubes, and graphene oxide; The transition metal catalyst is prepared according to the following method: a soluble salt of a transition metal is dissolved in water and then impregnated on a carrier, dried at 50-140°C for more than 6 hours, and then calcined at 250-550°C for a calcination time of not less than 0.5 hours to obtain a catalyst MO x / vector.

2. The method according to claim 1, characterized in that: The reaction temperature is 50-200°C, the reaction time is 0.5-12h, the oxygen pressure is 0.1-5.0MPa, the solvent is water, the furfural concentration is 0.02-5mol / L, the amount of transition metal catalyst is 0.1-10 times the mass of the reactants, and the molar ratio of the alkaline co-catalyst to furfural is 0.1-10.

3. The method according to claim 1, characterized in that: The reaction temperature is 60-140°C, the reaction time is 0.8-8h, the oxygen pressure is 0.5-3.0MPa, the solvent is water, the furfural concentration is 0.04-3mol / L, the amount of transition metal catalyst is 0.2-3 times the mass of the reactants, and the molar ratio of the alkaline co-catalyst to furfural is 0.2-6.

4. The method according to claim 1, characterized in that: The transition metal catalyst is prepared according to the following method: the impregnation time is 2-12 hours, the drying temperature is 60-130° C., the calcination temperature is 350-500° C., and the calcination time is 2-6 hours.

5. The method according to claim 4, characterized in that: The transition metal catalyst is prepared according to the following method: the soluble salt of the active component is one or more of cobalt nitrate, rhodium nitrate, iridium nitrate, nickel nitrate, palladium nitrate, platinum chloride, ruthenium chloride, copper nitrate, tetrachloroauric acid and silver nitrate.

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