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Method for preparing anhydrous formaldehyde through methanol dehydrogenation

A technology for anhydrous formaldehyde and methanol, which is applied in the fields of dehydrogenation preparation, carbon-based compound preparation, chemical instruments and methods, etc. It can solve the problems of inertness, difficulty in adjusting the acidity and alkalinity of molecular sieve catalysts, and small active surface area.

Inactive Publication Date: 2020-06-02
DALIAN INST OF CHEM PHYSICS CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] Based on the above, the disadvantages of the catalysts currently used in the preparation of anhydrous formaldehyde are: the distribution of copper particles in the copper-based catalyst is uneven, the particles are large, the active surface area is small, and the activity is low; the acidity and alkalinity of the modified molecular sieve catalyst is difficult to control. There are many by-products; the catalytic activity of traditional carbonate or bicarbonate is relatively inert, and the reaction temperature is generally higher than 700°C
The complex catalyst is a homogeneous catalytic process, and the separation consumes a lot of energy

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0014] Preparation of (0.5wt%Pd-0.5wt%In) / SiO by Co-precipitation 2 Catalyst, the operation is as follows: Weigh 2g nano-SiO 2 (50nm), dispersed into 20mL of water, respectively added a certain amount of Na 2 PdCl 4 and InCl 3 4H 2 O, stirred for 1 h, and adjusted the pH value of the suspension to 11 with 30% ammonia water. Stir for 1 hour, centrifuge and wash until neutral, dry in an oven at 80°C, and dry at 500°C 2 Reduction in medium for 2h, prepared (0.5wt%Pd-0.5wt%In) / SiO 2 catalyst. Weigh 2 g of the catalyst to form a tablet and fill it into a fixed-bed reactor. Under normal pressure, nitrogen gas is used as carrier gas, methanol is injected by a parallel flow pump, the volume ratio of methanol is 10vol%, the feed rate of methanol is 0.30mL / (gcat.min), the reaction is at 350°C, and the conversion rate of methanol is 73% as detected by gas chromatography on-line %, formaldehyde selectivity is 66%.

Embodiment 2

[0016] Preparation of (0.5wt%Pd-1.0wt%In) / SiO by Co-precipitation 2 Catalyst, the operation is as follows: Weigh 2g nano-SiO 2 (50nm), dispersed into 20mL of water, respectively added a certain amount of Na 2 PdCl 4 and InCl 3 4H 2 O, stirred for 1 h, and adjusted the pH value of the suspension to 11 with 30% ammonia water. Stir for 1 hour, centrifuge and wash until neutral, dry in an oven at 80°C, and dry at 450°C 2 Reduction in medium for 2h, prepared (0.5wt%Pd-1.0wt%In) / SiO 2 catalyst. Weigh 2 g of the catalyst to form a tablet and fill it into a fixed-bed reactor. Under normal pressure, nitrogen gas is used as the carrier gas, methanol is injected by a parallel flow pump, the volume ratio of methanol is 15vol%, the feed rate of methanol is 0.25mL / (gcat. min), the reaction is at 450°C, and the conversion rate of methanol is 77% as detected by gas chromatography on-line. %, formaldehyde selectivity is 85%.

Embodiment 3

[0018] Preparation of (1.5wt%Pd-0.5wt%In) / SiO by Co-precipitation 2 Catalyst, the operation is as follows: Weigh 2g nano-SiO 2 (50nm), dispersed into 20mL of water, respectively added a certain amount of Na 2 PdCl 4 and InCl 3 4H 2 O, stirred for 1 h, and adjusted the pH value of the suspension to 11 with 30% ammonia water. Stir for 1 hour, centrifuge and wash until neutral, dry in an oven at 80°C, and dry at 500°C 2 Reduction in medium for 2h, prepared (1.5wt%Pd-0.5wt%In) / SiO 2 catalyst. Weigh 2 g of the catalyst to form a tablet and fill it into a fixed-bed reactor. Under normal pressure, nitrogen gas is used as the carrier gas, methanol is injected by a parallel flow pump, the volume ratio of methanol is 30vol%, the feed rate of methanol is 0.20mL / (gcat.min), the reaction is at 450°C, and the conversion rate of methanol is 60% by gas chromatography on-line detection %, formaldehyde selectivity is 75%.

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Abstract

The invention relates to a method for preparing anhydrous formaldehyde through methanol dehydrogenation, wherein a palladium-indium catalyst (PdIn / SiO2) supported by silicon dioxide is adopted. The method specifically comprises the following steps: molding a PdIn / SiO2 catalyst, filling into a reaction tube, loading into a fixed bed reactor, carrying out a reaction at 350-600 DEG C under normal pressure, wherein methanol is injected by a constant-flux pump, inert gas is used as carrier gas, the methanol feeding ratio is 10-60 vol%, the methanol feeding speed is 0.10-0.30 mL / (gcat.min), the methanol conversion rate measured by chromatography is 60-80%, and the formaldehyde selectivity is 65-85%. According to the method for preparing anhydrous formaldehyde through methanol dehydrogenation, PdIn / SiO2 is adopted as the catalyst, high catalytic activity and high product selectivity are achieved, by-products are few, the catalyst preparation process is simple, and the thermal stability is high.

Description

technical field [0001] The invention relates to a method for preparing formaldehyde, in particular to a method for preparing anhydrous formaldehyde by dehydrogenating methanol. Background technique [0002] Formaldehyde is an important organic chemical raw material, which can be used to produce thermosetting resins such as phenolic resin and melamine resin, as well as bulk chemicals such as polyoxymethylene, phenolic aldehyde, urotropine, and 1,4-butanediol. Formaldehyde is also a synthetic dye , pesticides, disinfectants, adhesives and other products. [0003] At present, methanol oxidation is generally used in industry to prepare formaldehyde. In theory, formaldehyde aqueous solution with a molar ratio of 1:1 can be obtained, but the vapor pressure of formaldehyde aqueous solution is low, and formaldehyde and water form an azeotrope, so it is very difficult to separate and purify formaldehyde. Energy consumption is huge. In recent years, there is an increasing demand for...

Claims

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Application Information

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IPC IPC(8): C07C45/00C07C47/055
CPCC07C45/002C07C47/04
Inventor 王峰吕建民韩建宇任濮宁
Owner DALIAN INST OF CHEM PHYSICS CHINESE ACAD OF SCI