Application of activation-free and stable-performance catalyst in preparation of acetaldehyde through ethanol oxidation

Abstract

The invention belongs to the technical field of industrial catalysis, and particularly relates to application of a catalyst which does not need to be activated and is stable in performance in preparation of acetaldehyde through ethanol oxidation. The ternary bulk type catalyst with the composite oxide structure is filled in a tube of a shell-and-tube reactor, so that ethanol and oxygen and nitrogen flow through the catalyst in the tube, and the catalyst can directly and efficiently catalyze and convert ethanol into acetaldehyde without pretreatment processes such as reduction or oxidation. The method is high in raw material conversion rate and product selectivity, long in continuous operation period, relatively low in temperature control and three-agent cost, simple in operation step and good in industrial application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of industrial catalysis and relates to the application of a catalyst that does not require activation and has stable performance in ethanol oxidation to produce acetaldehyde. Background Art

[0002] Acetaldehyde is a dicarbon reagent and electrophilic reagent in organic synthesis, and is an important organic chemical intermediate. It has prochirality and high industrial application value. It is mainly used as a reducing agent, bactericide, fragrance, and for preparing standard solutions when determining aldehydes by colorimetry; it is used in industry to manufacture polyacetaldehyde, butanediol, acetic acid, vinyl acetate, ethyl acetate, acetic anhydride, ethanol, acetal, synthetic rubber, synthetic resin, pentaerythritol, n-butanol, crotonaldehyde, pyridine, pesticides, medicines, etc.

[0003] The main methods for producing acetaldehyde in industry are ethanol oxidation, ethylene oxidation and acetylene hydration. Among them, acetylene hydration is an early method for producing acetaldehyde, but due to the problem of mercury hazard, it has been gradually replaced by ethylene oxidation. The ethylene oxidation method uses petrochemical product ethylene as raw material and is obtained by liquid-phase oxidation in hydrochloric acid solution with palladium chloride / copper chloride as catalyst. This method has the problems of high cost, serious equipment corrosion, danger, environmental pollution, catalyst recovery, and difficulty in large-scale continuous production. Since ethylene is heavily dependent on fossil energy, the successful industrialization of ethanol synthesis from biomass routes and coal-based routes will improve the efficiency of ethanol production and further reduce costs. The ethanol oxidation method is in line with the concept of green and sustainable development. It has the advantages of high atomic economy, fast reaction rate, environmental friendliness, easy separation, and suitability for large-scale continuous production. Therefore, the ethanol oxidation method is expected to become the mainstream method for producing acetaldehyde worldwide.

[0004] The mature ethanol oxidation method is to pass a mixture of ethanol vapor and air into a fixed bed reactor equipped with an Ag catalyst, and an oxidation reaction occurs at 450℃-640℃ to generate acetaldehyde. Among them, the single-pass conversion rate of ethanol is 30-75%, the acetaldehyde selectivity is 85-95%, and the catalyst is replaced every 2-3 months. Although this method has certain advantages over the ethylene oxidation method and the acetylene hydration method, it still has shortcomings such as high operating temperature, low raw material conversion rate and product selectivity, expensive catalyst and short life, which increases the consumption of the process and reduces the economic efficiency. Summary of the invention

[0005] The purpose of the present invention is to provide a catalyst that does not require activation and has stable performance for use in ethanol oxidation to acetaldehyde in response to the technical problems existing in the prior art. The catalyst performs excellently when used for ethanol oxidation to acetaldehyde, effectively reduces process consumption, and improves technical economy.

[0006] To achieve the purpose of the present invention, the following technical solutions are adopted:

[0007] The present invention protects the use of a catalyst that does not require activation and has stable performance in the oxidation of ethanol to produce acetaldehyde. The specific method is: the catalyst is loaded into the tube of a shell-and-tube reactor, and ethanol and oxygen and nitrogen flow through the catalyst in the tube to catalyze the reaction of ethanol and oxygen to generate acetaldehyde; that is, when ethanol and oxygen and nitrogen flow through this catalyst that does not require activation and has stable performance, this (ternary bulk type with a composite oxide structure) catalyst efficiently catalyzes the conversion of ethanol into acetaldehyde.

[0008] Further, in this application, the feed liquid space velocity of the ethanol is 6.0-10.0h -1 (Specifically 6.0h -1 , 6.5h -1 , 7.0h -1 , 7.5h -1 , 8.0h -1 , 8.5h -1 , 9.0h -1 , 9.5h -1 , 10.0h -1 wait).

[0009] Furthermore, in this application, the mass fraction of oxygen at the reactor inlet is 8.0-20.0% (specifically 8.0%, 9.0%, 10.0%, 11.0%, 12.0%, 13.0%, 14.0%, 15.0%, 16.0%, 17.0%, 18.0%, 19.0%, 20.0%, etc.).

[0010] Furthermore, in this application, the controlled temperature of the reaction of ethanol and oxygen is 230-290°C (specifically 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, etc.), and the pressure is 0-40kPa (specifically 0kPa, 10kPa, 20kPa, 30kPa, 40kPa, etc.).

[0011] A catalyst that does not require activation and has stable performance is used in the above application. The catalyst is composed of Mo, Fe, X, and O elements, and its chemical formula is Mo α ·Fe β ·X γ ·O δ ; Wherein, X is Se or Te, α is 0.9-3.0, β is 0.6-1.5, γ is 0.001-0.1, and δ is a positive number that keeps the algebraic sum of the valences of each element equal to 0.

[0012] Furthermore, the active component of the catalyst is Fe2(MoO4)3, and X is an additive.

[0013] Furthermore, the molar ratio of Mo to Fe in the catalyst is 1.50-1.74.

[0014] The catalyst described above is a ternary bulk catalyst having a composite oxide structure.

[0015] A method for preparing a catalyst that does not require activation and has stable performance is prepared by a step-by-step wet mixing process, and the specific steps are:

[0016] First, a certain amount of industrial-grade MoO3, Fe(NO)3·9H2O, H2SeO4 (SeO2 is also acceptable) or H6TeO6 (TeO3 is also acceptable) is calculated and weighed according to the atomic stoichiometry; secondly, Fe(NO)3·9H2O, H2SeO4 (SeO2 is also acceptable) or H6TeO6 (TeO3 is also acceptable) is fully ground and mixed to obtain material A; then, MoO3 is fully ground in a small amount of solvent (methanol, ethanol, ethylene glycol or propylene glycol) to obtain material B; then A is added to B, fully ground and mixed to obtain material C; finally, C is calcined and formed to obtain a ternary bulk inorganic material Mo with a composite oxide structure. α ·Fe β ·X γ ·O δ .

[0017] The step-by-step wet mixing process does not require filtering, washing, or drying, and has fewer steps; the grinding and mixing process is carried out at room temperature, with low energy consumption and a short time; the entire process generates no wastewater or solid waste, thereby solving the problems of molybdenum loss and iron loss, and is green, economical, and environmentally friendly; and the processing cost of the ternary bulk inorganic material with a composite oxide structure is greatly reduced.

[0018] In addition, the crystal water in Fe(NO)3·9H2O is conducive to the full grinding and uniform mixing of Fe(NO)3·9H2O, H2SeO4 (SeO2 is also acceptable) or H6TeO6 (TeO3 is also acceptable); methanol, ethanol, ethylene glycol or propylene glycol are all hydroxyl-rich solvents, and the excellent affinity adsorption of hydroxyl groups not only helps MoO3 to be fully ground and evenly dispersed, but also helps Fe(NO)3·9H2O, H2SeO4 (SeO2 is also acceptable) or H6TeO6 (TeO3 is also acceptable) to form a strong interaction with the surface of molybdenum trioxide, and helps MoO3, Fe(NO)3·9H2O, H2SeO4 (SeO2 is also acceptable) or H6TeO6 (TeO3 is also acceptable) to be fully ground and evenly mixed, and finally a stable and repeatable ternary bulk catalyst Mo with a composite oxide structure is formed after calcination. α ·Fe β ·X γ ·O δ, in order to give full play to the synergistic effect of each component and improve the activity, selectivity and stability of the catalyst.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The present invention abandons the traditional, expensive silver catalyst and adopts a relatively cheap iron-molybdenum catalyst, and the catalyst has a low molybdenum-iron ratio and Se or Te content, which greatly reduces the cost of the three doses.

[0021] 2. The special formula design makes the catalyst used perform well when used for ethanol oxidation to acetaldehyde: the single-pass conversion rate of ethanol can reach 95%, and the selectivity of acetaldehyde can reach 97%. (1) Se or Te in the catalyst used is a VIA oxygen group element, with a maximum valence of +6, and can also exist in valences of -2, -1, 0, +1, +2, +4, etc. Depending on the environment, these two elements can change their valence. Se or Te exists in a high-valence state as an auxiliary agent. When the ethanol oxidation reaction occurs, Se or Te is reduced to a low-valence state, and then quickly oxidized to a high-valence state by O2 in the reaction gas flow, and the cycle repeats. Se or Te, as an efficient oxygen carrier, transfers oxygen in the gas flow to the product, and synergizes with Fe2(MoO4)3, which is conducive to the full conversion of ethanol into acetaldehyde, thereby improving the raw material conversion rate and product selectivity; (2) The molybdenum-iron ratio of the catalyst used is relatively low, only 1.50-1.74. This design value ensures that Mo and Fe are fully combined while increasing the mass fraction of the active component Fe2(MoO4)3 in the catalyst, thereby improving its catalytic performance.

[0022] 3. When the present invention is used for ethanol oxidation to produce acetaldehyde, unlike other methods, the catalyst used does not need to be activated with H2 or O2 before use, can be directly fed and operated, and has a low operating temperature, high ethanol single-pass conversion rate and acetaldehyde selectivity, long stable operation time, reduced process consumption, and improved technical and economic performance.

[0023] 4. Catalyst Mo used in the present invention α ·Fe β ·X γ ·O δ It is a ternary bulk inorganic material with a composite oxide structure. The components of the catalyst have good dispersibility, stable and repeatable structure and performance, and significant synergistic effect. It performs excellently when used in the production of ethanol oxidation to acetaldehyde and has good prospects for industrial application. DETAILED DESCRIPTION

[0024] All features disclosed in this specification, or steps in all methods or processes disclosed, except mutually exclusive features and / or steps, can be combined in any manner.

[0025] Any feature disclosed in this specification (including claims and abstract), unless otherwise stated, may be replaced by other equivalent or alternative features having similar purposes. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features.

[0026] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0027] Embodiment 1:

[0028] First, 272.6 g, 500.0 g, and 9.9 g of industrial-grade MoO3, Fe(NO)3·9H2O, and H2SeO4 were weighed, respectively; secondly, the weighed Fe(NO)3·9H2O and H2SeO4 were mixed, fully ground and mixed to obtain material A; then, 93 mL of methanol was added to the weighed MoO3, mixed and fully ground to make it uniformly dispersed to obtain material B; then A was added to B, fully ground and mixed to obtain material C; finally, C was calcined at 340°C for 9.0 h, and then formed to obtain a ternary bulk catalyst Mo with a composite oxide structure. 2.22 ·Fe 1.45 ·Se 0.08 ·O 8.995 .

[0029] The obtained ternary bulk catalyst Mo with a composite oxide structure 2.22 ·Fe 1.45 ·Se 0.08 ·O 8.995 The catalyst Mo is loaded into the tube of the shell and tube reactor and ethanol and oxygen and nitrogen are directly passed through the tube without activation. 2.22 ·Fe 1.45 ·Se 0.08 ·O 8.995 (Control the ethanol feed liquid space velocity to 7.0h -1 , the mass fraction of oxygen at the reactor inlet is 19.8%), and ethanol and oxygen are catalyzed to react under the conditions of controlling the temperature at 280°C and the pressure at 30 kPa. The reaction products are condensed, and the obtained liquid and gas products are analyzed by chromatography respectively. According to the calculation of carbon balance and catalytic performance indicators, the single-pass conversion rate of ethanol is 100.0%, and the formaldehyde selectivity is 97.0%.

[0030] Example 2

[0031] First, 305.4 g, 500.0 g, and 18.0 g of industrial-grade MoO3, Fe(NO)3·9H2O, and TeO3 were weighed respectively; secondly, the weighed Fe(NO)3·9H2O and TeO3 were mixed, fully ground and mixed evenly to obtain material A; then, 52 mL of propylene glycol was added to the weighed MoO3, mixed and fully ground to make it uniformly dispersed to obtain material B; then A was added to B, fully ground and mixed evenly to obtain material C; finally, C was calcined at 370°C for 6.5 h, and then formed to obtain a ternary bulk catalyst Mo with a composite oxide structure. 1.2 ·Fe 0.7 ·Te 0.058 ·O 4.824 .

[0032] The obtained ternary bulk catalyst Mo with a composite oxide structure 1.2 ·Fe 0.7 ·Te 0.058 ·O 4.824 The catalyst Mo is loaded into the tube of the shell and tube reactor and ethanol and oxygen and nitrogen are directly passed through the tube without activation. 1.2 ·Fe 0.7 ·Te 0.058 ·O 4.824 (Control the feed liquid space velocity of ethanol to 9.0h -1 , the mass fraction of oxygen at the reactor inlet is 10.0%), and ethanol and oxygen are catalyzed to react under the conditions of controlling the temperature at 230°C and the pressure at 2kPa. The reaction products are condensed, and the obtained liquid and gas products are analyzed by chromatography respectively. According to the calculation of carbon balance and catalytic performance indicators, the ethanol conversion rate is 95.8% and the acetaldehyde selectivity is 99.1%.

[0033] Example 3

[0034] First, 284.7 g, 500.0 g, and 0.5 g of industrial-grade MoO3, Fe(NO)3·9H2O, and SeO2 were weighed respectively; secondly, the weighed Fe(NO)3·9H2O and SeO2 were mixed, fully ground and mixed evenly to obtain material A; then, 116 mL of ethanol was added to the weighed MoO3, mixed and fully ground to make it uniformly dispersed to obtain material B; then A was added to B, fully ground and mixed evenly to obtain material C; finally, C was calcined at 360°C for 7.0 h, and then formed to obtain a ternary bulk catalyst Mo with a composite oxide structure. 1.71 ·Fe 1.07 ·Se 0.004 ·O 6.743 .

[0035] The obtained ternary bulk catalyst Mo with a composite oxide structure 1.71·Fe 1.07 ·Se 0.004 ·O 6.743 The catalyst Mo is loaded into the tube of the shell and tube reactor and ethanol and oxygen and nitrogen are directly passed through the tube without activation. 1.71 ·Fe 1.07 ·Se 0.004 ·O 6.743 (Control the feed liquid space velocity of ethanol to 8.0h -1 , the mass fraction of oxygen at the reactor inlet is 14.5%), ethanol and oxygen are catalyzed to react under the conditions of controlling the temperature at 260°C and the pressure at 18kPa (the reaction products are condensed, and the obtained liquid and gas products are analyzed by chromatography respectively), and the reaction is continuously operated for 2500h. The carbon balance and catalytic performance index are calculated, and the results at the beginning and end of the reaction are selected and listed in the following table:

[0036] Time Ethanol single-pass conversion rate % Acetaldehyde selectivity % 0 97.8 98.3 2500 96.1 98.2

[0037] Comparative Example 1

[0038] First, 446.0 g, 500.0 g, and 9.9 g of industrial-grade MoO3, Fe(NO)3·9H2O, and H2SeO4 were weighed respectively; secondly, the weighed Fe(NO)3·9H2O and H2SeO4 were mixed, fully ground and mixed evenly to obtain material A; then, 125 mL of methanol was added to the weighed MoO3, mixed and fully ground to make it uniformly dispersed to obtain material B; then A was added to B, fully ground and mixed evenly to obtain material C; finally, C was calcined at 340°C for 9.0 h, and then formed to obtain a ternary bulk catalyst Mo with a composite oxide structure. 3.63 ·Fe 1.45 ·Se 0.08 ·O 13.225 .

[0039] The obtained ternary bulk catalyst Mo with a composite oxide structure 3.63 ·Fe 1.45 ·Se 0.08 ·O 13.225 The catalyst Mo is loaded into the tube of the shell and tube reactor and ethanol and oxygen and nitrogen are directly passed through the tube without activation. 3.63 ·Fe 1.45 ·Se 0.08 ·O 13.225 (Control the feed liquid space velocity of ethanol to 20.0h -1, the mass fraction of oxygen at the reactor inlet is 5.0%), and ethanol and oxygen are catalyzed to react under the conditions of controlling the temperature at 280°C and the pressure at 30 kPa. The reaction products are condensed, and the obtained liquid and gas products are analyzed by chromatography respectively. The carbon balance and catalytic performance indexes are calculated, and the single-pass conversion rate of ethanol is 83.9%, and the formaldehyde selectivity is 81.1%.

[0040] Comparative Example 2

[0041] First, 305.4 g and 500.0 g of industrial-grade MoO3 and Fe(NO)3·9H2O were weighed respectively; secondly, the weighed Fe(NO)3·9H2O was fully ground to obtain material A; then, 52 mL of propylene glycol was added to the weighed MoO3, mixed and fully ground to make it uniformly dispersed to obtain material B; then A was added to B and fully ground and mixed to obtain material C; finally, C was calcined at 370°C for 6.5 h, and then formed to obtain a ternary bulk catalyst Mo with a composite oxide structure. 1.2 ·Fe 0.7 ·O 4.65 .

[0042] The obtained ternary bulk catalyst Mo with a composite oxide structure 1.2 ·Fe 0.7 ·O 4.65 The catalyst Mo is loaded into the tube of the shell and tube reactor and ethanol and oxygen and nitrogen are directly passed through the tube without activation. 1.2 ·Fe 0.7 ·O 4.65 (Control the feed liquid space velocity of ethanol to 9.0h -1 , the mass fraction of oxygen at the reactor inlet is 10.0%), and ethanol and oxygen are catalyzed to react under the conditions of controlling the temperature at 360°C and the pressure at 2 kPa. The reaction products are condensed, and the obtained liquid and gas products are analyzed by chromatography respectively. According to the calculation of carbon balance and catalytic performance indicators, the ethanol conversion rate is 90.5% and the acetaldehyde selectivity is 89.7%.

[0043] Comparative Example 3

[0044] First, 284.7 g, 500.0 g, and 25.7 g of industrial-grade MoO3, Fe(NO)3·9H2O, and SeO2 were weighed respectively; secondly, the weighed Fe(NO)3·9H2O and SeO2 were mixed, fully ground and mixed to obtain material A; then, 116 mL of ethanol was added to the weighed MoO3, mixed and fully ground to make it uniformly dispersed to obtain material B; then A was added to B, fully ground and mixed to obtain material C; finally, C was calcined at 360°C for 7.0 h, and then formed to obtain a ternary bulk catalyst Mo with a composite oxide structure. 1.71 ·Fe1.07 ·Se 0.2 ·O 6.935 The obtained ternary bulk catalyst Mo with a composite oxide structure 1.71 ·Fe 1.07 ·Se 0.2 ·O 6.935 The catalyst Mo is loaded into the tube of the shell and tube reactor and ethanol and oxygen and nitrogen are directly passed through the tube without activation. 1.71 ·Fe 1.07 ·Se 0.2 ·O 6.935 (Control the feed liquid space velocity of ethanol to 8.0h -1 , the mass fraction of oxygen at the reactor inlet is 14.5%), ethanol and oxygen are catalyzed to react under the conditions of controlling the temperature at 260°C and the pressure at 180kPa (the reaction products are condensed, and the obtained liquid and gas products are analyzed by chromatography respectively), and the reaction is continuously operated for 2500h. The carbon balance and catalytic performance index are calculated, and the results at the beginning and end of the reaction are selected and listed in the following table:

[0045] Time Ethanol single-pass conversion rate % Acetaldehyde selectivity % 0 88.0 87.6 2500 72.5 84.1

[0046] The above-mentioned embodiments only express the specific implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the protection scope of the present application. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the technical solution concept of the present application, and these all belong to the protection scope of the present application.

[0047] This background section is provided to generally present the context of the invention, and the work of the currently named inventors, the work described in this background section, and aspects of the description in this section that did not constitute prior art at the time of application are neither explicitly nor implicitly admitted to be prior art to the present invention.

Claims

1. Application of a catalyst that does not require activation and has stable performance in ethanol oxidation to acetaldehyde, characterized in that: This ternary bulk catalyst with a composite oxide structure is loaded into the tube of a shell-and-tube reactor, and ethanol and oxygen and nitrogen flow through the catalyst in the tube. The catalyst does not require any pretreatment process such as reduction or oxidation, and directly and efficiently catalyzes the reaction of ethanol and oxygen to produce acetaldehyde.

2. The use according to claim 1, characterized in that: The feed liquid space velocity of the ethanol is 6.0-10.0h -1 .

3. The use according to claim 1, characterized in that: The mass fraction of oxygen at the reactor inlet is 8.0-20.0%.

4. The use according to claim 1, characterized in that: The temperature of the reaction of ethanol and oxygen is 230-290°C and the pressure is 0-40 kPa.

5. A catalyst that does not require activation and has stable performance, used in the application as claimed in any one of claims 1 to 4, characterized in that: The catalyst is composed of Mo, Fe, X, and O elements, and its chemical formula is Mo α ·Fe β ·X γ ·O δ ; Wherein, X is Se or Te, α is 0.9-3.0, β is 0.6-1.5, γ is 0.001-0.1, and δ is a positive number that keeps the algebraic sum of the valences of each element equal to 0.

6. The catalyst according to claim 5, characterized in that: The active component of the catalyst is Fe2(MoO4)3, X is an additive; the molar ratio of Mo to Fe in the catalyst is 1.50-1.

74.

7. The method for preparing a catalyst that does not require activation and has stable performance according to claim 5, characterized in that The following steps are involved: 1) MoO3, Fe(NO)3·9H2O, and raw materials containing Se or Te are weighed in proportion, and then fully ground and mixed to obtain material A; 2) Grinding MoO3 fully under the action of a solvent to obtain material B; 3) Add material A to material B, grind them thoroughly and mix them evenly to obtain material C; 4) Calcinate and shape material C to obtain a ternary bulk catalyst having a composite oxide structure, namely, Mo α ·Fe β ·X γ ·O δ .

8. The method for preparing the catalyst according to claim 7, characterized in that: The raw material containing Se or Te in step 1) is H2SeO4 or SeO2, H6TeO6 or TeO3.

9. The method for preparing the catalyst according to claim 5, characterized in that: The solvent described in step 2) is methanol, ethanol, ethylene glycol or glycerol.

10. The method for preparing the catalyst according to claim 5, characterized in that: The calcination temperature in step 4) is 330-380°C and the calcination time is 6.0-10.0h.