CN113121345A

CN113121345A - Application of monatomic Pd catalyst in CO gas-phase carbonylation

Info

Publication number: CN113121345A
Application number: CN202110192919.5A
Authority: CN
Inventors: 连超; 施建兴; 彭斌; 邓明亮; 王敏朵
Original assignee: Beijing Single Atom Catalysis Technology Co ltd
Current assignee: Beijing Single Atom Catalysis Technology Co ltd
Priority date: 2021-02-20
Filing date: 2021-02-20
Publication date: 2021-07-16
Anticipated expiration: 2041-02-20
Also published as: CN113121345B

Abstract

The invention discloses an application of a monatomic catalyst in preparation of ester chemicals such as oxalate, carbonate and the like through CO gas-phase carbonylation.

Description

Application of monatomic Pd catalyst in CO gas-phase carbonylation

Technical Field

The invention relates to synthesis of ester compounds such as oxalate, carbonate and the like, in particular to application of a monoatomic Pd catalyst-catalyzed CO gas-phase carbonylation to preparation of corresponding ester chemicals.

Background

High value-added ester chemicals such as oxalate and carbonate can be efficiently prepared by carrying out gas-phase carbonylation on CO from synthesis gas. Dimethyl carbonate, for example, obtained by carbonylation reactions, is an important starting material for the preparation of aromatic polycarbonates, the synthesis of aliphatic and aromatic mono-and diisocyanates, and is also used as a methylating agent, as a replacement for the toxic phosgene required for the preparation of pharmaceuticals and agrochemicals, as a solvent and additive for increasing the octane number of vaporized fuels and as an intermediate product for the preparation of synthetic lubricants. The oxalates obtained by carbonylation coupling are useful as intermediates for the preparation of ethylene glycol, oxalic acid, oxalyl chloride, oxamides, certain drugs, dyes and solvents.

Nano-catalysts of supported noble metal palladium are often used for CO gas phase carbonylation reactions. For example, patent JP8242.656 laid-open patent publication reports a process flow for synthesizing dimethyl oxalate at normal pressure using CO and methyl nitrite using a supported palladium catalyst; patent CN1323754C reports a supported palladium catalyst for low pressure gas phase carbonylation synthesis of dimethyl carbonate. Although the supported noble metal palladium nano-catalyst is proved to have good catalytic efficiency for CO gas-phase carbonylation reaction at present, in recent years, the price of the international noble metal palladium is greatly increased, the cost of the palladium-based catalyst gradually becomes a huge burden for using enterprises, the market still needs a low-cost and high-activity catalyst, and how to realize high-efficiency conversion of CO gas-phase carbonylation at a lower content has great economic value. Particularly, in the use process of the currently used supported nano palladium catalyst, the palladium nano catalyst is easy to grow, reduce the activity and inactivate due to specific process conditions, the service life cannot meet the design requirement, and the industrial production is difficult to realize. Therefore, the development of the monatomic supported catalyst with excellent performance and long service life has important scientific significance and practical value.

Disclosure of Invention

The invention discloses an application of a supported monatomic palladium catalyst in CO gas-phase carbonylation coproduction of oxalate and carbonate, wherein palladium is supported on a carrier in a monatomic site state, the supported amount of the palladium is 0.01-0.5 wt% based on the total weight of the catalyst, and the supported amount of the palladium is preferably 0.1-0.5 wt%, and the carrier is a common supported carrier, such as carbon, alumina, silica, a molecular sieve, a metal phosphate, a heteropolyacid salt and the like.

Preferably, the supported monatomic palladium is monatomic palladium carbon Pd₁A catalyst comprising palladium supported in a monoatomic site state on an activated carbon support, wherein the amount of palladium supported is 0.01 to 0.5% by weight, based on the total weight of the catalyst, preferably 0.1 to 0.5% by weight. The carbon carrier is carbon materials such as activated carbon, nitrogen-doped carbon, graphite, carbon fiber, carbon nano tube and the like.

The invention discloses a preparation method of a supported monatomic palladium catalyst, which comprises the following steps:

step A: dissolving soluble palladium salt in aqua regia, adding carrier, and stirring

And B: and evaporating aqua regia to dryness, and roasting to obtain the supported monatomic palladium catalyst.

In step a, the soluble palladium salt is selected from inorganic salts, organic salts or complexes, preferably nitrate, chloride, sulfate, acetate, oxalate, acetylacetonate or chloro complex, and sodium chloropalladate is implemented in the present invention.

The carrier is selected from materials such as carbon, alumina, silicon oxide, molecular sieves, metal phosphates, heteropolyacid salts and the like, and carbon materials such as activated carbon, nitrogen-doped carbon, graphite, carbon fibers, carbon nanotubes and the like are preferred.

In step B, the evaporation is carried out at a temperature of between 50 and 100 ℃ and preferably between 60 and 80 ℃ and can be carried out at normal pressure or under reduced pressure. The calcination is carried out in a non-oxidizing atmosphere, wherein the atmosphere comprises introducing nitrogen, argon, helium or hydrogen or vacuum, and the calcination temperature is 100-300 ℃, preferably 120-180 ℃.

The invention further discloses a method for producing carbonic ester and/or oxalic ester by taking CO as raw material, which comprises the step of using the supported monatomic catalyst such as Pd₁In the presence of/C catalyst, CO reacts with nitrite RONO to obtain product, and carbonate and/or oxalate are separated according to requirement.

Wherein in the nitrite RONO, R is selected from C_1-6Alkyl groups such as methyl nitrite, ethyl nitrite, propyl nitrite and butyl nitrite.

Has the advantages that:

1. the invention uses the monatomic noble metal catalyst, and because the noble metal Pd in the monatomic state is not aggregated, the atom utilization rate of the noble metal Pd is 100 percent of the Pd atoms exposed on the surface of the catalyst (the Pd atom part of the nano Pd catalyst inside aggregated nano particles is not always effective), and the high-efficiency CO gas-phase carbonylation catalytic conversion can be realized at lower noble metal Pd usage amount.

2. Comparing the nano palladium catalyst (Pd content 0.5%) with the monoatomic palladium catalyst (Pd content 0.2%), the monoatomic palladium catalyst has higher catalytic activity and selectivity.

3. The service life of the palladium single-atom catalyst under the same condition is more than several times of that of the palladium nanocrystalline catalyst. Can completely meet the requirement of production process design.

Drawings

FIG. 1 is an SEM photograph of a monoatomic Pd catalyst obtained in example 1

FIG. 2 is a transmission electron micrograph of a monatomic Pd catalyst obtained in example 1

FIG. 3 is a transmission electron micrograph of the nano Pd catalyst obtained in comparative example 1

DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION

The noun explains:

MN: methyl nitrite.

CO: carbon monoxide

TCD: thermal conductivity detector

FID: flame ionization detector

RONO: esters of nitrous acid

TEM: transmission electron microscope

Example 1

The preparation method of the monatomic Pd/C catalyst comprises the following steps: 0.0556g of sodium chloropalladate is dissolved in 20ml of aqua regia, 10g of carbon powder is added, and the mixture is stirred for 1 hour at room temperature. Evaporating aqua regia to dryness at 60-80 ℃, and roasting for 4h at 160 ℃ in a nitrogen atmosphere to obtain the monatomic Pd/C catalyst (with Pd content of 0.2%).

Evaluation of catalyst: 0.2g of a monoatomic Pd/C catalyst was packed in a quartz tube having a tube length of 760mm and an inner diameter of 8 mm. Reactant gas (MN/N)₂And CO) flow rate is controlled by a mass flow meter, and the gas is mixedAnd then, the reaction apparatus was evaluated. And detecting and analyzing the components of the reaction tail gas by adopting an online gas chromatograph provided with a thermal conductivity cell detector and a hydrogen flame detector. Wherein TCD detects CO and N₂And FID detects methyl nitrite, dimethyl carbonate, dimethyl oxalate, methyl formate and methanol. In addition, the pipeline between the outlet end of the reaction device and the six-way valve of the FID needs to be kept at 120 ℃ (the pipeline is prevented from being blocked after dimethyl carbonate is condensed). The reaction results are shown in Table 1.

Comparative example 1

The specific preparation steps of the nano palladium Pd/C catalyst are as follows: 0.1g of palladium nitrate was impregnated in an equal volume onto 10g of carbon powder. Standing and aging for 30min, drying at 100 ℃ for 3h, and roasting at 500 ℃ for 30min under nitrogen atmosphere to obtain the nano Pd/C catalyst (Pd content is 0.5%).

Evaluation of catalyst: 0.2g of the nano Pd/C catalyst was packed in a quartz tube having a tube length of 760mm and an inner diameter of 8 mm. Reactant gas (MN/N)₂And CO) flow rate is controlled by a mass flow meter, and the gas is mixed and then enters a reaction device for evaluation. And detecting and analyzing the components of the reaction tail gas by adopting an online gas chromatograph provided with a thermal conductivity cell detector and a hydrogen flame detector. Wherein TCD detects CO and N₂And FID detects methyl nitrite, dimethyl carbonate, dimethyl oxalate, methyl formate and methanol. In addition, the pipeline between the outlet end of the reaction device and the six-way valve of the FID needs to be kept at 120 ℃ (the pipeline is prevented from being blocked after dimethyl carbonate is condensed). The reaction results are shown in Table 2.

Test experiments and data

Catalyst characterization:

the spherical aberration electron micrograph of fig. 1 clearly observed the monoatomic bright spot of Pd, whereas in fig. 2 (transmission electron micrograph of catalyst prepared in example 1), only the carbon support was observed, and no Pd species was observed, because the monoatomic Pd was too small to exceed the TEM detection limit, which also indicates that Pd was distributed on the carbon support in a monoatomic state. In contrast, in the transmission electron micrograph of fig. 3, it can be observed that the catalyst prepared in comparative example 1 contains significant Pd nanoparticles. As can be seen from the characterization graphs, in the catalyst prepared in example 1, Pd was supported on a carbon support in a monoatomic state, whereas the catalyst prepared in comparative example 1 was prepared such that nano Pd particles were supported on a carbon support.

Application test data:

related test methods the description of example 1 and comparative example 1, applying test data results are presented in tables 1 and 2.

Table 1: catalytic Performance of the catalyst of example 1 in gas phase carbonylation of MN-CO (Pd content 0.2%)

Table 2: catalytic Performance of the catalyst of comparative example 1 in gas phase carbonylation of MN-CO (Pd content 0.5%)

And (4) conclusion:

from the activity test result, under the condition that the Pd content is reduced to 40 percent, the catalytic performance is obviously improved, particularly the MN conversion rate is improved by about 5 to 10 percent, and the total selectivity of dimethyl carbonate and dimethyl oxalate is also obviously improved.

Therefore, compared with the nano palladium carbon catalyst, the single-atom palladium carbon catalyst has higher efficiency and better selectivity in the reaction of catalyzing CO and MN to prepare dimethyl carbonate and/or dimethyl oxalate, and has better industrial application prospect.

In addition, the noble metal catalyst with the same carrier can maintain the catalytic activity and even improve the catalytic activity under the condition that the using amount of the catalyst is obviously reduced after the noble metal is monoatomic.

Claims

1. The application of a supported monatomic palladium catalyst in CO gas-phase carbonylation coproduction of oxalate and carbonate is characterized in that palladium is supported on a carrier in a monatomic site state, wherein the supported amount of the palladium is 0.01-0.5 wt% and preferably 0.1-0.5 wt% based on the total weight of the catalyst, and the carrier is a carbon, alumina, silica, molecular sieve, metal phosphate or heteropoly acid salt carrier.

2. Use according to claim 1, wherein the catalyst is a monoatomic palladium on carbon catalyst, and the palladium is supported on a carbon support in a monoatomic state, wherein the palladium is supported in an amount of 0.01 to 0.5 wt%, preferably 0.1 to 0.5 wt%, based on the total weight of the catalyst.

3. Use as claimed in claim 1 or 2, wherein the catalyst carbon support is selected from activated carbon, nitrogen-doped carbon, graphite, carbon fibres or carbon nanotube material.

4. A method for preparing a supported monatomic palladium catalyst, comprising:

step A: dissolving soluble palladium salt in aqua regia, adding carrier, and mixing

In step a, the soluble palladium salt is selected from inorganic salts, organic salts or complexes, preferably nitrate, chloride, sulfate, acetate, oxalate, acetylacetonate or chloro complex, and the carrier is preferably a carbon carrier material, such as activated carbon, graphite, carbon fiber, carbon nanotube or carbon material doped with nitrogen.

5. The method according to claim 4, wherein the soluble palladium salt is preferably sodium chloropalladate, palladium nitrate, palladium chloride, and the support is preferably selected from carbon, nitrogen-doped carbon.

6. The process according to claim 4 or 5, wherein in step B, the evaporation is carried out at 50 to 100 ℃, preferably 60 to 80 ℃, and may be carried out under normal pressure or reduced pressure; the calcination is carried out in a non-oxidizing atmosphere comprising nitrogen, argon, helium or hydrogen at a temperature of 100-300 deg.C, preferably 120-180 deg.C.

7. A method for producing carbonate and/or oxalate by using CO as raw material, which comprises the steps of claim 13 or the catalyst prepared according to the method of claims 4-6, reacting CO with nitrite RONO to obtain a product, and separating to obtain carbonate and/or oxalate according to the requirement, wherein in the nitrite RONO, R is selected from C_1-6An alkyl group.

8. The method of claim 7, wherein nitrite RONO is methyl nitrite, ethyl nitrite, propyl nitrite, or butyl nitrite.