Preparation method of modified molecular sieve loaded Pd catalyst and application of modified thereof in synthesis of dimethyl carbonate by gas phase process

A technology of dimethyl carbonate and molecular sieve, which is applied in the field of catalyst preparation, can solve problems such as poor safety, low catalyst selectivity, and reduced conversion rate

Active Publication Date: 2020-06-26
CHINA UNIV OF PETROLEUM (EAST CHINA)
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The phosgene method is being phased out due to the disadvantages of high raw material toxicity, poor safety, and serious environmental pollution; although the transesterification method has the advantages of simple operation and mild reaction conditions, it is relatively difficult to separate and purify the target product, and the cost is relatively high The uric acid alcoholysis method also encounters the problem of subsequent separation difficulties due to the use of a homogeneous catalyst; although the one-step synthesis method of methanol and carbon dioxide is simple, the activity of the catalyst is relatively low
The conversion rate of methanol and carbon dioxide reported in the Chinese patent CN110479287A is only 11.2%, the selectivity of dimethyl carbonate is 75.6%, and the yield is only 8.5%.
Chinese patent application publication number CN106423289A publicly reports a kind of catalyst used for synthesizing dimethyl carbonate and preparation method thereof, adopts copper and potassium as the auxiliary agent of molecular sieve loaded Pd catalyst, and the space-time yield of this catalyst is 690g/(Lh), yet The selectivity of dimethyl carbonate based on methyl nitrite is only 45% to 51%, which shows that the selectivity of the catalyst is relatively low
A molecular sieve-loaded Pd catalyst was prepared by Japan Ube Corporation Yamamoto et al. The selec

Method used

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  • Preparation method of modified molecular sieve loaded Pd catalyst and application of modified thereof in synthesis of dimethyl carbonate by gas phase process
  • Preparation method of modified molecular sieve loaded Pd catalyst and application of modified thereof in synthesis of dimethyl carbonate by gas phase process
  • Preparation method of modified molecular sieve loaded Pd catalyst and application of modified thereof in synthesis of dimethyl carbonate by gas phase process

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Experimental program
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Effect test

Embodiment 1

[0039] 1) Using a mixed solution containing 0.02mol / L sodium bicarbonate and 0.03mol / L sodium chloride to pretreat the FAU molecular sieve at 20°C for 0.6 hours, wash, dry at 80°C for 4 hours, and roast at 155°C for 2 hours , to obtain a modified molecular sieve;

[0040] 2) Add the modified molecular sieve in step 1) to deionized water to form a suspension, use 0.25mmol / L dilute ammonia solution to dissolve palladium chloride to obtain a mixed solution, add the mixed solution dropwise to the suspension, and control the palladium element The mass ratio to the modified molecular sieve is 0.002:1, the pH is adjusted to 5.5 with hydrochloric acid aqueous solution, and the reaction is stirred at 6°C for 0.6 hours. After filtering and washing, dry at 10°C for 47 hours, and then use a muffle furnace to The heating rate of 0.25°C / min was raised to 115°C, and kept in the muffle furnace for 0.6 hours to obtain a Pd-loaded molecular sieve;

[0041] 3) Put the Pd-loaded molecular sieve ...

Embodiment 2

[0044] 1) FAU molecular sieves were pretreated at 40°C for 6.0 hours with a mixed solution containing 0.20mol / L acetic acid and 0.10mol / L oxalic acid, washed, dried at 80°C for 4 hours, and calcined at 300°C for 2 hours to obtain a modified Molecular sieve;

[0045] 2) Step 1) the modified molecular sieve is added to deionized water to form a suspension, and the dilute ammonia solution of 2.4mmol / L is used to dissolve palladium nitrate and palladium acetate to obtain a mixed solution, and the mixed solution is added dropwise to the suspension to control The mass ratio of palladium element to modified molecular sieve is 0.011:1, the pH is adjusted to 7.5 by using nitric acid and acetic acid aqueous solution, stirred and reacted at 35°C for 24 hours, filtered and washed, dried at 45°C for 24 hours, and then used The muffle furnace was raised to 180°C at a rate of 0.5°C / min, and kept in the muffle furnace for 2 hours to obtain a Pd-loaded molecular sieve;

[0046] 3) Put the Pd-...

Embodiment 3

[0049] 1) Pretreating the FAU molecular sieve with 0.48mol / L potassium chloride solution at 70°C for 22 hours, washing, drying at 80°C for 4 hours, and roasting at 400°C for 2 hours to obtain a modified molecular sieve;

[0050] 2) Add step 1) modified molecular sieve to deionized water to form a suspension, utilize 4.8mmol / L dilute ammonia solution to dissolve potassium chloropalladate and palladium chloride to obtain a mixed solution, and add the mixed solution dropwise to the suspension In the process, the mass ratio of palladium element to modified molecular sieve is controlled to be 0.024:1, the pH is adjusted to 8.0 by using hydrochloric acid aqueous solution, the reaction is stirred at 92°C for 46 hours, filtered and washed, dried at 90°C for 1.5 hours, and then Use a muffle furnace to raise the temperature to 240°C at a rate of 1.8°C / min, and keep it in the muffle furnace for 3.8 hours to obtain a Pd-loaded molecular sieve;

[0051] 3) Put the Pd-loaded molecular sieve...

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Abstract

The invention belongs to the technical field of catalyst preparation, and particularly relates to a preparation method of a modified molecular sieve loaded Pd catalyst and application thereof in synthesis of dimethyl carbonate by a gas phase process. The carrier of the catalyst is a modified FAU or EMT molecular sieve, main active components are zero-valent palladium (Pd) and valence state Pd, themass fraction of Pd in the catalyst is 0.1%-2.5%, and the average particle size of Pd particles is 0.2-15 nanometers. The catalyst is applied to a reaction for synthesizing dimethyl carbonate from carbon monoxide and methyl nitrite by a low-pressure gas phase process, solves the problems of equipment corrosion and inactivation caused by a traditional chlorine-containing catalyst, and is a high-performance catalyst which is high in stability, selectivity and conversion rate, resistant to sintering, free of chlorine and adjustable in Pd nanoparticle size. The preparation method of the catalystis simple, low in equipment requirement and low in production cost, is suitable for large-scale production, and has certain industrial application prospect.

Description

technical field [0001] The invention belongs to the technical field of catalyst preparation, and in particular relates to a preparation method of a modified molecular sieve supported Pd catalyst and its application in gas-phase synthesis of dimethyl carbonate. Background technique [0002] Dimethyl carbonate (Dimethyl carbonate, DMC) is an important environment-friendly chemical raw material. It has been listed as a non-toxic chemical as early as 1992. It can be used to produce polycarbonate, pharmaceuticals, pesticides and other products, instead of phosgene and halogenated Methane and dimethyl sulfate are used as carbonylation and methylation reagents, and are used as solvents in the lithium battery electrolyte and paint coating industries (accounting for more than 50% of my country's total DMC consumption), and are expected to replace toxic methyl tert-butyl ether ( MTBE) as gasoline and diesel additives. According to statistics, the market demand for DMC in my country has...

Claims

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Application Information

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IPC IPC(8): B01J29/12B01J29/74B01J35/10B01J37/02B01J37/08C07C68/00C07C69/96
CPCB01J35/006B01J35/0066B01J35/1023B01J35/1038B01J37/0207B01J37/08B01J29/12B01J29/7438C07C68/00B01J2229/18B01J2229/14C07C69/96
Inventor 王纯正徐宁堃许伟松周顺健谢沛延覃正兴郭海玲白鹏刘欣梅
Owner CHINA UNIV OF PETROLEUM (EAST CHINA)
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