Disclosed are processes for conversion of a feedstock comprising C.sub.8+ aromatic hydrocarbons to lighter aromatic products in which the feedstock and optionally hydrogen are contacted in the presence of the catalyst composition under conversion conditions effective to dealkylate and transalkylate said C.sub.8+ aromatic hydrocarbons to produce said lighter aromatic products comprising benzene, toluene and xylene. The catalyst composition comprises a zeolite, a first metal, and a second metal, and is treated with a source of sulfur and/or a source of steam.

A cold start catalyst is disclosed. The cold start catalyst is effective to adsorb NO.sub.x and hydrocarbons (HC) at or below a low temperature and to covert and release the adsorbed NO.sub.x and HC at temperatures above the low temperature. The cold start catalyst comprises a molecular sieve catalyst and a supported platinum group metal catalyst. The molecular sieve catalyst consists essentially of a noble metal and a molecular sieve. The supported platinum group metal catalyst comprises one or more platinum group metals and one or more inorganic oxide carriers. The invention also includes an exhaust system comprising the cold start catalyst, and a method for treating exhaust gas from an internal combustion engine utilizing the cold start catalyst.

Disclosed are processes for conversion of a feedstock comprising C.sub.8+ aromatic hydrocarbons to lighter aromatic products in which the feedstock and optionally hydrogen are contacted in the presence of the catalyst composition under conversion conditions effective to dealkylate and transalkylate said C.sub.8+ aromatic hydrocarbons to produce said lighter aromatic products comprising benzene, toluene and xylene. The catalyst composition comprises a zeolite, a first metal, and a second metal, and is treated with a source of sulfur and/or a source of steam.

A catalyst for synthesizing aromatic hydrocarbons, a preparation method thereof and a method for synthesizing aromatic hydrocarbons by using the catalyst. The catalyst comprises acidic molecular sieve particles and zinc-aluminum composite oxide particles. The catalyst has relatively high selectivity to aromatic hydrocarbons, particularly BTX, stable performance, and a long single-pass life.

Disclosed are processes for conversion of a feedstock comprising C.sub.8+ aromatic hydrocarbons to lighter aromatic products in which the feedstock and optionally hydrogen are contacted in the presence of the catalyst composition under conversion conditions effective to dealkylate and transalkylate said C.sub.8+ aromatic hydrocarbons to produce said lighter aromatic products comprising benzene, toluene and xylene. The catalyst composition comprises a zeolite, a first metal, and a second metal, and is treated with a source of sulfur and/or a source of steam.

Disclosed are processes for conversion of a feedstock comprising C.sub.8+ aromatic hydrocarbons to lighter aromatic products in which the feedstock and optionally hydrogen are contacted in the presence of the catalyst composition under conversion conditions effective to dealkylate and transalkylate said C.sub.8+ aromatic hydrocarbons to produce said lighter aromatic products comprising benzene, toluene and xylene. The catalyst composition comprises a zeolite, a first metal, and a second metal, and is treated with a source of sulfur and/or a source of steam.

Disclosed are processes for conversion of a feedstock comprising C.sub.8+ aromatic hydrocarbons to lighter aromatic products in which the feedstock and optionally hydrogen are contacted in the presence of a first and a second catalyst composition under conversion conditions effective to produce said lighter aromatic products comprising benzene, toluene and xylene. In the process, the C.sub.8+ aromatic hydrocarbons are dealkylated to form C.sub.6-C.sub.7 aromatic hydrocarbon and the C.sub.2+ olefins formed are saturated. The remaining C.sub.8+ aromatic hydrocarbons are transalkylated with the C.sub.6-C.sub.7 aromatic hydrocarbon. The first and second catalyst compositions each comprise a zeolite, a first metal, and optionally a second metal, and are treated with a source of sulfur and/or a source of steam.

A catalyst for synthesizing aromatic hydrocarbons, a preparation method thereof and a method for synthesizing aromatic hydrocarbons by using the catalyst. The catalyst comprises acidic molecular sieve particles and zinc-aluminum composite oxide particles. The catalyst has relatively high selectivity to aromatic hydrocarbons, particularly BTX, stable performance, and a long single-pass life.

The present invention provides a method for producing methyl acetate, and the method comprises a step in which dimethyl ether and a raw gas containing carbon monoxide and hydrogen go through a reactor loaded with a catalyst for carrying out a carbonylation reaction; wherein the catalyst contains an acidic EMT zeolite molecular sieve. The present invention has provided a new method for producing methyl acetate. In the method of the present invention, the carbonylation is carried out in the presence of the catalyst containing the acidic EMT zeolite molecular sieve, and the reaction activity is high, and the stability has been significantly improved, meeting the requirement of industrial production.

The present invention provides a method for producing methyl acetate, and the method comprises a step in which dimethyl ether and a raw gas containing carbon monoxide and hydrogen go through a reactor loaded with a catalyst for carrying out a carbonylation reaction; wherein the catalyst contains an acidic EMT zeolite molecular sieve. The present invention has provided a new method for producing methyl acetate. In the method of the present invention, the carbonylation is carried out in the presence of the catalyst containing the acidic EMT zeolite molecular sieve, and the reaction activity is high, and the stability has been significantly improved, meeting the requirement of industrial production.