AU2018447125B2

AU2018447125B2 - Carbonylation catalyst and preparation thereof

Info

Publication number: AU2018447125B2
Application number: AU2018447125A
Authority: AU
Inventors: Jian Huang
Original assignee: Pujing Chemical Industry Co Ltd
Current assignee: Pujing Chemical Industry Co Ltd
Priority date: 2018-10-22
Filing date: 2018-10-22
Publication date: 2022-11-24
Anticipated expiration: 2038-10-22
Also published as: RU2702107C1; AU2018447125A1; WO2020082200A1

Abstract

The invention relates to a carbonylation catalyst for synthesizing an oxalate from carbon monoxide (CO) and nitrite in a gas phase is provided. The catalyst comprises an active component, an auxiliary agent and a carrier. The active component comprises palladium (Pd) particles. The auxiliary agent comprises an auxiliary element selected from the group consisting of an alkali metal, an alkaline earth metal, IB, IIB, IVB, VB, VIB, VIIB, VIII, IIIA, IVA and a lanthanide. The carrier comprises an oxide or a composite oxide. Also provided is a process for making the catalyst and a method for using the catalyst in synthesizing an oxalate in a gas phase reaction between CO and methyl nitrite (MN).

Description

CARBONYLATION CATALYST AND PREPARATION THEREOF

FIELD OF THE INVENTION

The present invention relates to a carbonylation catalyst for gas phase synthesis of dimethyl oxalate from carbon monoxide (CO) and methyl nitrite and preparation thereof.

BACKGROUND OF THE INVENTION

Dimethyl oxalate is not only the most competitive source of raw materials for synthesis of oxalic acid by hydrolysis, but also used as the raw materials for making ethylene glycol and glycolic acid by hydrogenation. It has extremely important commercial application value. It is a well-known chemical reaction to synthesize an oxalate by carbonylation of CO in a gas phase. In the presence of a Pd/Al ₂O ₃ catalyst, CO and methyl nitrite form an oxalate in a carbonylation coupling reaction and generate nitrogen oxide (NO) . Patent document CN 95116136.9 discloses a Pd-Zr/Al ₂O ₃ catalyst for synthesis of an oxalate having Zr as a promoter. The catalyst is prepared by an impregnation method, and is applied in the synthesis of the dimethyl oxalate by carbonylation of CO with methyl nitrite in a gas phase in a fixed bed reactor. However, the catalyst in CN 95116136.9 provides a low yield of an oxalate and has a high requirement for the impurity content of the raw material gas. The oxalate selectivity was 95%, and the one-way methyl nitrite conversion was up to 64%. Both need to be further improved. The reaction process for oxalate synthesis is as follows:

Carbonylation reaction: 2CO+2RONO→2NO+ (COOR) ₂ (1)

Regeneration reaction: 2ROH+0.5O ₂+2NO→2RONO+H ₂O (2)

In view of the above reaction process, in theory, this system does not consume NO or RONO (alkyl nitrite) . In reality, in addition to the main product oxalate in the step (1) of the reaction process, side reactions often happen and thus the selectivity of an oxalate is reduced, resulting in a low space-time yield of the oxalate. The raw material gas usually uses the CO separated from coal syngas by pressure swing adsorption, and its H ₂ content is usually higher than 1000 ppm. The presence of H ₂ promotes the side reaction of methyl formate and reduces the selectivity of the oxalate. Further, in order to control the content of O ₂ in the raw material gas, the concentration of NO is generally increased to lower the O ₂ concentration to ensure that the raw material gas introduced into the carbonylation reactor meets the reaction conditions. The carbonylation is a rapid reaction that achieves a reaction equilibrium in a short period of time. An excessive NO concentration inhibits the synthesis of an oxalate.

To further scale up the existing oxalate synthesis reactor, there is a need for a highly efficient carbonylation catalyst against H ₂ and NO.

SUMMARY OF THE INVENTION

The present invention provides a catalyst and its preparation and uses.

A carbonylation catalyst for synthesizing an oxalate from carbon monoxide (CO) and nitrite in a gas phase is provided. The catalyst comprises (a) an active component comprising palladium (Pd) particles, (b) an auxiliary agent comprising an auxiliary element selected from the group consisting of an alkali metal, an alkaline earth metal, IB, IIB, IVB, VB, VIB, VIIB, VIII, IIIA, IVA and a lanthanide, and (c) a carrier comprising an oxide or a composite oxide.

The carrier may have a rich outer surface. The ratio of bridged adsorption CO to linear adsorption CO is 1.8-4.3.

The Pd particles may have a dispersion of 25-40 %. The Pd particles may have an average particle size of 2.5-4.0 nm. The catalyst may comprise the active component at 0.01-1.00 wt%.

The carbonylation catalyst may comprises the auxiliary agent at (a) 0.01-12 wt%where the auxiliary element is the alkali metal or the alkaline earth metal; (b) 0.01-11 wt %where the auxiliary element is selected from the group consisting of IB, IIB, IVB, VB, VIB, VIIB, VIII, IIIA and IVA; or (c) 0.01-10 wt %where the auxiliary element is a lanthanide.

The carrier may be selected from the group consisting of alumina, magnesia, zinc oxide and a composite oxide thereof. Where the carrier comprises alumina, at least 90 wt%of the alumina may be in the form of alpha-alumina. Where the carrier comprises a composite oxide, at least 80 wt%of the composite oxide may be in the form of a spinel.

The carrier may have a size of 1-10 mm. The carrier may have a specific surface area of 2-100 m ²/g. The carrier may have an average pore diameter of 0.6-100 nm. The carrier may have an outer surface area that is 3-30 times of an outer surface of a spherical carrier of an equivalent diameter d (d=cube root (6*V/3.14) d is the equivalent diameter and V is the volume of a particle) .

For each catalyst of the present invention, a process for preparing the catalyst is provided. The process comprises (a) impregnating the carrier with a first impregnation solution to make a first carrier sample; (b) drying the first carrier sample to make a first dry carrier sample; (c) calcining the first dry carrier sample to make a first loaded carrier; (d) impregnating the first loaded carrier with a second impregnation solution to make a second carrier sample; (e) drying the second carrier sample to make a second dry carrier sample; (f) calcining the second carrier sample; wherein the first impregnation solution comprises the auxiliary agent and the second impregnation solution comprises the active component, or the first impregnation solution comprises the active component and the second impregnation solution comprises the auxiliary agent As a result, the catalyst comprising the active component, the auxiliary agent and the carrier is prepared.

Each of the first impregnation solution and the second impregnation solution may have a pH of 0.5-14.

The impregnation step of step (a) or (d) may comprise soaking the carrier in an impregnation solution for 0.03-24 h or spraying the impregnation solution onto the carrier at 60-90 ℃.

The drying step (b) or (e) may be carried out at 90-120 ℃ for 6-12 h.

The calcine step (c) or (f) may be carried out at 120-500 ℃ for 3-8 h, and/or may be carried out in the presence of a calcining gas selected from the group consisting of air, nitrogen (N ₂) , nitrogen oxide (NO) and a combination thereof.

The calcining gas maybe a mixed gas of NO and N ₂.

The Pd salt may be selected from the group consisting of a nitrate, a halide, an oxalate, an acetate and a combination thereof. The process of claim 20, wherein the Pd salt may be an acetate. The Pd salt may be a combination of an oxalate and a nitrate at an oxalate/nitrate mass ratio of 0.01-10.

For each catalyst of the present invention, a process for preparing the catalyst is provided. The process may comprise (a) impregnating the carrier with an active component/auxiliary agent impregnation solution to make a carrier sample; (b) drying the carrier sample to make a dry carrier sample; and (c) calcining the dry carrier sample, whereby the catalyst comprising the active component, the auxiliary agent and the carrier is prepared.

A method for synthesizing an oxalate by a gas phase reaction between carbon monoxide (CO) and methyl nitrite (MN) is provided. The method comprising exposing a feed gas to an effective amount of the catalyst. As a result, an oxalate is synthesized with an MN conversion greater than 90%, an oxalate selectivity greater than 99%, an oxalate space-time yield greater than 1,400 g /kgcat/h for at least 8,000 h. The feed gas may have a H ₂ content of 500-1500 ppm.

DETAILED DESCRIPTION OF THE INVENTION

The invention relates to a carbonylation catalyst for synthesizing an oxalate from CO and nitrite, and a preparation method thereof. According to existing oxalate synthesis technologies, the space-time yield of an oxalate is low, and the industrial reactor is limited in size; in industrial production, the purity of the raw material gas is relatively demanding, that is, the H ₂ content in the CO gas is generally less than 100 ppm. Fluctuations in the H ₂ content in the raw material gas can easily cause fluctuations in the selectivity of the oxalate, which is detrimental to stable operation of a subsequent hydrogenation unit. The novel carbonylation catalyst of this invention is highly resistant to H ₂ and provides a high space-time yield. The invention is based on the inventors’s urprising discovery of a novel way to make a carbonylation catalyst, when used in oxalate synthesis with a raw material gas having a H ₂ content up to 1500 ppm and a NO content up to 15 v%, provides a MN conversion greater than 90%, an oxalate selectivity greater than 99%, stable operation for more than 8000 h, a space-time yield of an oxalate up to 1400 g/kgcat/h. The advantages of the carbonylation catalyst of this invention include not demanding for low H ₂ content (≤1500ppm) , high MN conversion with high NO content in the raw material gas, high efficiency, high stability, low precious metal loading, no need for a special dehydrogenation device, which is beneficial to reduce the investment cost for equipment and raw material gas purification, high selectivity, and high conversion.

A carbonylation catalyst used for synthesizing an oxalate from carbon monoxide (CO) and nitrite in a gas phase is provided. The catalyst comprises an active component, an auxiliary agent and a carrier.

The term “active component” used herein refers to a substance in the catalyst that catalyzes the reaction between CO and nitrite to synthesize an oxalate in a gas phase.

The term “auxiliary agent” used herein refers to a substance in the catalyst that promotes the interaction between an active component and a carrier in a catalyst. The auxiliary agent may promote formation of Pd particles having a desirable average particle size. The auxiliary agent may also increase adsorption of CO to the catalyst by, for example, increasing the ratio of bridged CO adsorption sites and linear CO adsorption sites on the catalyst.

The term “carrier” used herein refers to a substance in the catalyst that provides support for an active component and an auxiliary agent. Depending on its structure, the carrier may change the distribution of the active component on the carrier such that the catalytic activity of the active component may be modified. The term “dispersion degree” used herein refers to a system in which discrete particles of one material are dispersed in a continuous phase of another material.

The term “particle size” used herein refers to the diameter of a particle, which may be solid, liquid or gas. Where the particle is not spherical, the particle size may be the average diameter of the particle.

The term “loading” used herein refers to placing an active component, an auxiliary agent or both onto a carrier. When both the active component and the auxiliary agent are loaded onto the same carrier, a catalyst comprising the active component, auxiliary agent and the carrier is formed.

The term “impregnation solution” used herein refers to a solution for loading a soluble substance in the solution onto a solid. Where the solid is a carrier, the soluble substance may be used to load an active component, an auxiliary agent or both onto the carrier by impregnating the carrier with the solution.

The term “rich outer surface” used herein refers to a large surface of a carrier as compared with that of a spherical particle having an equivalent diameter as the carrier. The term “equivalent diameter” used herein refers to a calculated diameter (d) based on the volume of a particle (V) using the formula d=cube root (6*V/3.14) .

The term “bridged CO adsorption sites” used herein refers to the CO adsorption sites on the catalyst for contact with the carbon atom in the CO via two or more metal atoms in surface of the catalyst.

The term “linear CO adsorption sites” used herein refers to the adsorption sites on the catalyst for contact with the carbon atom in the CO with a single metal atom on the surface of the catalyst.

The term “specific surface area” used herein refers to a property of a solid defined as the total surface area of a material per unit of mass, or solid or bulk volume.

The terms “feed gas” and “raw material gas” are used herein interchangeably, and refer to a gas that is introduced into a chemical process.

The active component may comprise palladium (Pd) particles. The active component may account for about 0.01-1.00 wt%, preferably about 0.01-0.4 wt%, more preferably about 0.02-0.5 wt%, still more preferably about 0.03-0.28 wt%, most preferably about 0.04-0.18 wt%, of the catalyst. The Pd particles may have a dispersion degree of about 20- 50 %, preferably about 25-40 %. The Pd particles may have an average particle size in the range of about 2.0-5.0 nm, preferably about 2.5-4 nm.

The auxiliary agent comprises an element selected from the group consisting of an alkali metal, an alkaline earth metal, IB, IIB, IVB, VB, VIB, VIIB, VIII, IIIA, IVA and a lanthanide. Where the auxiliary element is an alkali metal or alkaline earth metal, the auxiliary agent accounts for about 0.01-12 wt%, preferably about 0.05-10 wt%, more preferably about 0.1-8 wt%, most preferably about 0.2-6 wt%, of the catalysts. Where the auxiliary element is selected from the group consisting of IB, IIB, IVB, VB, VIB, VIIB, VIII, IIIA and IVA, the auxiliary agent accounts for about 0.01-11 wt %, preferably about 0.01-8 wt%, more preferably about 0.1-6 wt%, most preferably about 0.15-4.5 wt%of the catalyst. Where the auxiliary element is a lanthanide, the auxiliary agent accounts for about 0.01-10 wt%, preferably about 0.01-7 wt%, more preferably about 0.03-6 wt%, most preferably about 0.1-5 wt%, of the catalyst. An active component/auxiliary agent impregnation solution comprises a Pd salt and a salt of an auxiliary element.

The carrier comprises an oxide or a composite oxide. The carrier may have a rich outer surface. The carrier may have an outer surface area that is about 3-30, 5-25, 8-20 or 10-20 times of the outer surface of a spherical carrier having an equivalent diameter. The ratio of bridged adsorption CO to linear adsorption CO on Pd metal particles is 1.8-4.3.

The carrier may be alumina, magnesia, zinc oxide or a composite oxide. Where the carrier comprises alumina, at least 90 wt%of the alumina is in the form of alpha-alumina. Wherein the carrier is a composite oxide, at least 80 wt%of the composite oxide is in the form of a spinel.

The carrier may have a size of about 1-10 mm, preferably about 1.2-7 mm, more preferably about 1.5-6 mm, still more preferably about 1.6-5.5 mm, most preferably about 2.1-5.2 mm.

The carrier may have a specific surface area of about 2-100 m ²/g, preferably about 3.5-80 m ²/g, more preferably about 4.5-65 m ²/g, still more preferably about 5.2-42 m ²/g, most preferably about 6.5-28.5 m ²/g. The catalyst may have a specific surface area of about 7-25 m ²/g.

The carrier may have an average pore diameter of about 0.6-100 nm, preferably about 1.5-70 nm, more preferably about 2.5-60 nm, still more preferably about 5.5-52 nm, most preferably about 10.5-38 nm. The catalyst may have an average pore diameter of about 15-35 mm.

For each catalyst of the present invention, a process for preparing the catalyst is provided. The preparation process comprises loading the active component onto the carrier and loading the auxiliary agent onto the carrier. These two steps may be carried out simultaneously or in sequence.

In each loading step, the carrier is impregnated with an impregnation solution before being dried and calcined. The impregnating step may comprise soaking the carrier in the impregnation solution for about 0.03-24 h spraying the impregnation solution onto the carrier at about 60-90 ℃. The drying step may be carried out at about 90-120 ℃ for about 6-12 h. The calcining step may be carried out at about 120-500 ℃, preferably about 200-450℃, most preferably about 220-380℃, for 3-8 h. The calcining step may be carried out in the presence of a calcining gas. The calcining gas may be selected from the group consisting of air, nitrogen (N ₂) , nitrogen oxide (NO) and a combination thereof. The calcining gas may be a mixed gas of NO and N ₂, for example, at a NO/N ₂ molar ratio of 0.01-2.00.

In one embodiment, the carrier is first loaded with the active component and then the auxiliary agent. The carrier is impregnated with an active component impregnation solution to make an active component carrier sample. The active component carrier sample is dried, for example, at about 90-120 ℃ for about 6-12 h, to make a dry active component carrier sample. The dry active component carrier sample is calcined, for example, at about 120-500 ℃, preferably about 200-450℃, most preferably about 220-380℃, for 3-8 h. As a result, a carrier loaded with the active component is prepared. The carrier loaded with the active component is then impregnated with an auxiliary agent impregnation solution to make an auxiliary agent carrier sample. The auxiliary agent carrier sample is dried, for example, at about 90-120 ℃ for about 6-12 h, to make a dry auxiliary agent carrier sample. The dry auxiliary agent carrier sample is calcined, for example, at about 120-500 ℃, preferably about 200-450℃, most preferably about 220-380℃, for 3-8 h. As a result, a carrier is loaded with both the active component and the auxiliary agent and the catalyst comprising the active component, the auxiliary agent and the carrier is prepared.

In another embodiment, the carrier is first loaded with the auxiliary agent and then the active component. The carrier is impregnated with an auxiliary agent impregnation solution to make an auxiliary agent carrier sample. The auxiliary agent carrier sample is dried, for example, at about 90-120 ℃ for about 6-12 h, to make a dry auxiliary agent carrier sample. The dry auxiliary agent carrier sample is calcined, for example, at about 120-500 ℃, preferably about 200-450℃, most preferably about 220-380℃, for 3-8 h. As a result, a carrier loaded with the auxiliary agent is prepared. The carrier loaded with the auxiliary agent is then impregnated with an active component impregnation solution to make an active component carrier sample. The active component carrier sample is dried, for example, at about 90-120 ℃ for about 6-12 h, to make a dry active component carrier sample. The dry active component carrier sample is calcined, for example, at about 120-500 ℃, preferably about 200-450℃, most preferably about 220-380℃, for 3-8 h. As a result, a carrier is loaded with both the active component and the auxiliary agent and the catalyst comprising the active component, the auxiliary agent and the carrier is prepared.

In yet another embodiment, the carrier is loaded with the active component and the auxiliary agent simultaneously. The carrier is impregnated with an active component/auxiliary agent impregnation solution to make an active component/auxiliary agent carrier sample. The active component/auxiliary agent carrier sample is dried, for example, at about 90-120 ℃ for about 6-12 h, to make a dry active component/auxiliary agent carrier sample. The dry active component/auxiliary agent carrier sample is calcined, for example, at about 120-500 ℃, preferably about 200-450℃, most preferably about 220-380℃, for 3-8 h. As a result, a carrier is loaded with both the active component and the auxiliary agent and the catalyst comprising the active component, the auxiliary agent and the carrier is prepared.

The active component impregnation solution comprises a Pd salt. The active component impregnation solution may have a pH of about 0.15-4, preferably about 6-12, more preferably about 8-11.

The auxiliary agent impregnation solution comprises a salt of an auxiliary element. The auxiliary agent impregnation solution may have a pH of about 0.15-4, preferably about 6-12, more preferably about 8-11.

The active component/auxiliary agent impregnation solution comprising a Pd salt and a salt of an auxiliary element. The active component/auxiliary agent impregnation solution may have a pH of about 0.15-4, preferably about 6-12, more preferably about 8-11.

The Pd salt may be a nitrate, a halide, an oxalate, an acetate or a combination thereof. The Pd salt may be an acetate. The Pd salt may be a combination of an oxalate and a nitrate at an oxalate/nitrate mass ratio of, for example, about 0.01-10, preferably about 0.01-2, more preferably about 0.01-0.5, most preferably about 0.02-0.2.

The salt of the auxiliary agent may be selected from the group consisting of a chloride, a nitrate, an acetate, an oxalate and an ammonium salt, preferably a chloride, a nitrate and an acetate; more preferably an acetate and a nitrate.

For each catalyst of the invention, a method for synthesizing an oxalate in a gas phase reaction between carbon monoxide (CO) and methyl nitrite (MN) is provided. The synthesis method comprises exposing a feed gas to an effective amount of the catalyst. As a result, an oxalate is synthesized. The MN conversion rate may be greater than 90%. The oxalate selectivity may be greater than 99%. The oxalate space-time yield may be greater than 1,400 g/kg _cat/h for at least 8,000 h. The feed gas may comprise a H ₂ content of 500-1500 ppm.

The term “conversion rate” used herein refers to the percentage of methyl nitrite (MN) that is converted to a product. The average MN conversion rate of the catalyst according to the present invention may be up to 91%after 8,000 h.

The term “selectivity” used herein refers to the percentage of methyl nitrite (MN converted to a target product in all of the converted methyl nitrite (MN) . The selectivity of the catalyst for dimethyl oxalate according to the present invention may be up to 99.1%for 8,000 h.

The term “space-time yield of dimethyl oxalate” used herein refers to the production amount of dimethyl oxalate per unit volume (or mass) of a catalyst per unit time. The space-time yield of dimethyl oxalate synthesized according to the present invention may be up to 1,400 g/ (L. h) .

The term “about” as used herein when referring to a measurable value such as an amount, a percentage, and the like, is meant to encompass variations of ±20%or ±10%, more preferably ±5%, even more preferably ±1%, and still more preferably ±0.1%from the specified value, as such variations are appropriate.

Example 1. Catalyst 1-11

Catalyst 1-11 were prepared according to the same process. A solution comprising palladium nitrate as an active component and nitrates of Na, Mg, Mn, Zn, Zr, Ga, Fe, Co, Ce, Gd or La with an auxiliary agent was prepared. 8 ml of the solution was adjusted to a pH of 2 with a dilute acid. 20 g of special structure α-alumina composite oxide carrier A (having an outer surface 20 times that of a spherical ball of equivalent diameter) was heated to 65 ℃. The solution was sprayed evenly onto the heated carrier while the carrier was turned around. The carrier loaded with the active component and the auxiliary agent was dried at 120 ℃ for 6 h, calcined in an atmosphere furnace at 350 ℃ for 3 h, naturally cooled, and then vacuum sealed.

Table 1 shows the physical characters of catalysts 1-11, including a carrier size equivalent diameter, a Pd content, an auxiliary agent content, a special surface area, an average carrier pore size and an average Pd particle diameter for each catalyst.

Example 2. Catalyst 12 and 13

Catalyst 12-13 were prepared according to the method described in Example 1 except that the auxiliary agent was an oxalate of Sn or Nb. Table 1 shows the physical characters of catalysts 12-13.

Example 3. Catalyst 14 and 15

Catalyst 14-15 were prepared according to the method described in Example 1 except that the auxiliary agent was sodium nitrate or was omitted while the pH was adjusted to 11 with ammonia. Table 1 shows the physical characters of catalysts 14-15.

Example 4. Catalyst 16-19

Catalyst 16-19 were prepared according to the method described in Example 1 except that the auxiliary agent was omitted and the carrier was the α-alumina B, the magnesium-aluminum composite oxide C, the zinc-aluminum composite oxide D, the magnesium-aluminum-zinc composite oxide E carrier 20 g were respectively heated to 75 ℃. Table 1 shows the physical characters of catalysts 16-19.

Example 5. Catalytic Activity

The catalysts 1-19 prepared in Examples 1-19 were subjected to CO gas phase coupling synthesis of an oxalate reaction using a fixed bed reactor. The catalysts were reduced in the presence of a N ₂ mixed gas containing 20 v%CO at 220 ℃ for 8 hours. Then, the raw material gas was introduced to the reduced catalysts for a carbonylation reaction. The composition of the raw material gas was: CO: 30 v%, CH ₃ONO: 12 v%, NO: 15 v%, H ₂: 0.15 v%and the balance was nitrogen. The reaction conditions were as follows: temperature 136 ℃, pressure 4.0 bar, gas hourly space velocity (GHSV) 4800 h ^-1. Table 2 shows a MN conversion rate, an oxalate selectivity and a gas hourly space velocity (GHSV) for each catalyst.

Table 1. Physical properties of catalysts

Table 2. Catalytic activities

Although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims without departing from the invention.

Claims

A carbonylation catalyst for synthesizing an oxalate from carbon monoxide (CO) and nitrite in a gas phase, comprising:

(a) an active component comprising palladium (Pd) particles;

(b) an auxiliary agent comprising an auxiliary element selected from the group consisting of an alkali metal, an alkaline earth metal, IB, IIB, IVB, VB, VIB, VIIB, VIII, IIIA, IVA and a lanthanide, and

(c) a carrier comprising an oxide or a composite oxide.
The carbonylation catalyst of claim 1, wherein the carrier has a rich outer surface.
The carbonylation catalyst of claim 1, wherein the ratio of bridged adsorption CO to linear adsorption CO on the catalyst is 1.8-4.3.
The carbonylation catalyst of claim 1, wherein the Pd particles have a dispersion rate of 20-50 %.
The carbonylation catalyst of claim 1, wherein the Pd particles have an average particle size of 2.5-4.0 nm.
The carbonylation catalyst of claim 1, wherein the catalyst comprises the active component at 0.01-1.00 wt%.
The carbonylation catalyst of claim 1, wherein the catalyst comprises the auxiliary agent at

(a) 0.01-12 wt%, wherein the auxiliary element is the alkali metal or the alkaline earth metal;

(b) 0.01-11 wt %, wherein the auxiliary element is selected from the group consisting of IB, IIB, IVB, VB, VIB, VIIB, VIII, IIIA and IVA; or

(c) 0.01-10 wt %, wherein the auxiliary element is a lanthanide.
The carbonylation catalyst of claim 1, wherein the carrier is selected from the group consisting of alumina, magnesia, zinc oxide and a composite oxide thereof.
The carbonylation catalyst of claim 8, wherein the carrier comprises alumina, and wherein at least 90 wt%of the alumina is in the form of alpha-alumina.
The carbonylation catalyst of claim 8, wherein the carrier comprises a composite oxide, and wherein at least 80 wt%of the composite oxide is in the form of a spinel.
The carbonylation catalyst of claim 1, wherein the carrier has a size of 1-10 mm.
The carbonylation catalyst of claim 1, wherein the carrier has a specific surface area of 2-100 m ²/g.
The carbonylation catalyst of claim 1, wherein the carrier has an average pore diameter of 0.6-100 nm.
The carbonylation catalyst of claim 1, wherein the carrier has an outer surface area that is 3-30 times of an outer surface of a spherical carrier of the same equivalent diameter.
A process for preparing the catalyst of claim 1, comprising:

(a) impregnating the carrier with a first impregnation solution to make a first carrier sample;

(b) drying the first carrier sample to make a first dry carrier sample;

(c) calcining the first dry carrier sample to make a first loaded carrier;

(d) impregnating the first loaded carrier with a second impregnation solution to make a second carrier sample;

(e) drying the second carrier sample to make a second dry carrier sample;

(f) calcining the second carrier sample;

wherein the first impregnation solution comprises the auxiliary agent and the second impregnation solution comprises the active component, or the first impregnation solution comprises the active component and the second impregnation solution comprises the auxiliary agent, whereby the catalyst comprising the active component, the auxiliary agent and the carrier is prepared.
A process for preparing the catalyst of claim 1, comprising:

(a) impregnating the carrier with an active component/auxiliary agent impregnation solution to make a carrier sample;

(b) drying the carrier sample to make a dry carrier sample;

(c) calcining the dry carrier sample, whereby the catalyst comprising the active component, the auxiliary agent and the carrier is prepared.
The process of claim 15, wherein each of the first impregnation solution and the second impregnation solution has a pH of 0.5-14.
The process of claim 15, wherein step (a) comprises soaking the carrier in the first impregnation solution for 0.03-24 h or spraying the first impregnation solution onto the carrier at 60-90 ℃, and wherein step (d) comprises soaking the first loaded carrier in the second impregnation solution for 0.03-24 h or spraying the second impregnation solution onto the first loaded carrier at 60-90 ℃
The process of claim 15, wherein steps (b) and (e) are carried out at 90-120 ℃ for 6-12 h.
The process of claim 15, wherein steps (c) and (f) are carried out at 120-500 ℃ for 3-8 h.
The process of claim 15, wherein steps (c) and (f) are carried out in the presence of a calcining gas selected from the group consisting of air, nitrogen (N ₂) , nitrogen oxide (NO) and a combination thereof.
The process of claim 18, wherein the calcining gas is a mixed gas of NO and N ₂.
The process of claim 15, wherein the Pd salt is selected from the group consisting of a nitrate, a halide, an oxalate, an acetate and a combination thereof.
The process of claim 23, wherein the Pd salt is an acetate.
The process of claim 23, wherein the Pd salt is a combination of an oxalate and a nitrate at an oxalate/nitrate mass ratio of 0.01-10.
A method for synthesizing an oxalate by a gas phase reaction between carbon monoxide (CO) and methyl nitrite (MN) , comprising exposing a feed gas to an effective amount of the catalyst of claim 1, whereby an oxalate is synthesized with an MN conversion rate greater than 90%, an oxalate selectivity greater than 99%, and an oxalate space-time yield greater than 1400 g /kgcat/h for at least 8, 000 h.
The method of claim 26, wherein feed gas comprises a H ₂ content of 500-1,500 ppm.