Provided are processes for monitoring and maintaining continuous carbonylation of epoxides or lactones. Processes include measuring parameters affecting the rate of the carbonylation reaction and adding supplemental replacement catalyst replacement components to maintain a constant rate of carbonylation.

A method of preparing -hydroxycarboxylic acid ester comprises mixing an alkylene oxide, a monohydric alcohol and a composite catalyst, and performing a carbonylation esterification reaction in a carbon monoxide atmosphere to obtain the -hydroxycarboxylic acid ester. The composite catalyst comprises a main catalyst, a cocatalyst and a reducing agent. the main catalyst is at least one of a cobalt salt, cobalt oxide and cobalt hydroxide. The cocatalyst is a nitrogen-containing heterocyclic compound. The reducing agent is a base metal. The method is an atomic reaction type process, does not produce three wastes, and has high conversion rate. It is a green environmental protection process. The composite catalyst used does not contain Co.sub.2(CO).sub.8. The raw materials and catalyst used are all cheap and easily available. The composite catalyst can be used repeatedly at a lower cost, and is suitable for industrial applications.

A method of preparing -hydroxycarboxylic acid ester comprises mixing an alkylene oxide, a monohydric alcohol and a composite catalyst, and performing a carbonylation esterification reaction in a carbon monoxide atmosphere to obtain the -hydroxycarboxylic acid ester. The composite catalyst comprises a main catalyst, a cocatalyst and a reducing agent. the main catalyst is at least one of a cobalt salt, cobalt oxide and cobalt hydroxide. The cocatalyst is a nitrogen-containing heterocyclic compound. The reducing agent is a base metal. The method is an atomic reaction type process, does not produce three wastes, and has high conversion rate. It is a green environmental protection process. The composite catalyst used does not contain Co.sub.2(CO).sub.8. The raw materials and catalyst used are all cheap and easily available. The composite catalyst can be used repeatedly at a lower cost, and is suitable for industrial applications.

A method of preparing -hydroxycarboxylic acid ester comprises mixing an alkylene oxide, a monohydric alcohol and a composite catalyst, and performing a carbonylation esterification reaction in a carbon monoxide atmosphere to obtain the -hydroxycarboxylic acid ester. The composite catalyst comprises a main catalyst, a cocatalyst and a reducing agent. the main catalyst is at least one of a cobalt salt, cobalt oxide and cobalt hydroxide. The cocatalyst is a nitrogen-containing heterocyclic compound. The reducing agent is a base metal. The method is an atomic reaction type process, does not produce three wastes, and has high conversion rate. It is a green environmental protection process. The composite catalyst used does not contain Co.sub.2(CO).sub.8. The raw materials and catalyst used are all cheap and easily available. The composite catalyst can be used repeatedly at a lower cost, and is suitable for industrial applications.

Provided are processes for monitoring and maintaining continuous carbonylation of epoxides or lactones. Processes include measuring parameters affecting the rate of the carbonylation reaction and adding supplemental replacement catalyst replacement components to maintain a constant rate of carbonylation.

Provided are processes for monitoring and maintaining continuous carbonylation of epoxides or lactones. Processes include measuring parameters affecting the rate of the carbonylation reaction and adding supplemental replacement catalyst replacement components to maintain a constant rate of carbonylation.

Provided are processes for monitoring and maintaining continuous carbonylation of epoxides or lactones. Processes include measuring parameters affecting the rate of the carbonylation reaction and adding supplemental replacement catalyst replacement components to maintain a constant rate of carbonylation.

A method for directly producing methyl acetate and/or acetic acid from syngas, carried out in at least two reaction zones, including: feeding a raw material containing syngas into a first reaction zone to contact and react with a metal catalyst; allowing an obtained effluent to enter a second reaction zone directly or after the addition of carbon monoxide so as to contact and react with a solid acid catalyst; separating the obtained effluent to obtain product of acetate and/or acetic acid, and optionally returning a residual part to enter the first reaction zone and/or the second reaction zone to recycle the reaction. This provides a novel method for directly converting syngas into methyl acetate and/or acetic acid. Further, the product selectivity of the product of methyl acetate or acetic acid is greater than 93%, and the quantity of methyl acetate and acetic acid may be adjusted according to processing.

A method for directly producing methyl acetate and/or acetic acid from syngas, carried out in at least two reaction zones, including: feeding a raw material containing syngas into a first reaction zone to contact and react with a metal catalyst; allowing an obtained effluent to enter a second reaction zone directly or after the addition of carbon monoxide so as to contact and react with a solid acid catalyst; separating the obtained effluent to obtain product of acetate and/or acetic acid, and optionally returning a residual part to enter the first reaction zone and/or the second reaction zone to recycle the reaction. This provides a novel method for directly converting syngas into methyl acetate and/or acetic acid. Further, the product selectivity of the product of methyl acetate or acetic acid is greater than 93%, and the quantity of methyl acetate and acetic acid may be adjusted according to processing.

A method for directly producing ethanol from syngas, carried out in three reaction zones, including: feeding a raw material containing syngas and dimethyl ether into a first reaction zone to contact with a solid acid catalyst, reacting; allowing the effluent from the first reaction zone to enter a second reaction zone to contact with a metal catalyst and react; separating the effluent from the second reaction zone to obtain product ethanol and by-product methanol; allowing by-product methanol to enter a third reaction zone to perform a dehydration reaction to obtain dimethyl ether, and allowing the obtained dimethyl ether to enter the first reaction zone to recycle the reaction. This provides a novel method for directly converting syngas to ethanol and an ethanol product can be directly produced by using syngas as a raw material.