441 results about "Catalyst selectivity" patented technology

A NOX abatement system includes a first NOX adsorber capable of being disposed in-line and downstream of and in fluid communication with an engine. The NOX abatement system further includes a selective catalytic reduction catalyst disposed in-line and downstream of, and in direct fluid communication with, the first NOX adsorber. The selective catalytic reduction catalyst is capable of storing ammonia. An off-line reformer is disposed in selective communication with and upstream of the first NOX adsorber and the selective catalytic reduction catalyst. The reformer is capable of producing a reformate that includes primarily hydrogen and carbon monoxide.

A method allowing the efficient conduction of highly exothermic, catalyst initiated reactions, particularly ones in which the product spectrum is highly dependant upon the temperature at which the process is conducted and to diffusional resistances within the catalyst particle matrix. The process occurs in a heat transfer device which consists of at least two channels which have at least one wall in common. Preferably two distinct sets of flow channels exist in which the process proceeds in one set of channels and heat transfer fluid passes through the second. The area of contact between the two sets of channels is sufficiently large to allow the efficient transfer of heat. These dimensions are controlled through the use of hollow catalyst particles through which the process gas can diffuse through either the inside or outside.

The present invention discloses a low energy consumption hydrocracking method for processing a poor-quality raw material. According to the method, a raw material and hydrogen gas are mixed, are subjected to heat exchange two times, pass through a heating furnace, and then are subjected to a hydrorefining reaction; the refining effluent is subjected to separation and fractionation; the obtained tail oil enters a hydrocracking reaction zone, wherein the cracking reaction zone comprises at least two cracking catalysts, the upstream is a catalyst I, the downstream is a catalyst II, the catalyst I contains 15-50 wt% of a modified Y molecular sieve, the catalyst II contains 3-30 wt% of the modified Y molecular sieve, and the modified Y molecular sieve content in the catalyst I is 10-25% higher than the modified Y molecular sieve content in the catalyst II; and the hydrocracking effluent and poor-quality raw material oil are mixed and then enter a hydrorefining reaction zone. According to the method of the present invention, the high temperature high pressure countercurrent heat transfer technology and the hydrocracking catalyst grading technology are organically combined, and the hydrocracking reaction heat is comprehensively utilized, such that the catalyst selectivity is maintained while the target product quality is improved, and the project investment and the operating energy consumption are reduced.

The invention discloses a hydrocracking method of low-nergy-onsumption productive high-quality chemical raw materials. After raw oil and hydrogen are mixed, the obtained mixture is subjected to heat transfer for two times and then passes through a heating furnace, the obtained object is sequentially subjected to hydrorefining and then passes through a first cracking reaction area, the obtained product is separated so as to obtain middle distillate, the middle distillate enters a second cracking reaction area to crack, wherein the first cracking reaction area is at least filled with two cracking catalysts, a catalyst I is filled in the upstream part, and a catalyst II is filled in the downstream part; and the catalyst I contains 30-70% of modified Y molecular sieve, the catalyst II contains 15-50% of modified Y molecular sieve, and the content of the modified Y molecular sieve in the catalyst I is 10-30% higher than the content of the modified Y molecular sieve in the catalyst II. In the method disclosed by the invention, a high-temperature and high-pressure countercurrent heat transfer technology and a hydrocracking catalyst grading technology are organically combined, and through the comprehensive utilization of hydrocracking reaction heat, while the selectivity of catalysts is maintained, the product quality is enhanced, and the construction investment and the energy consumption of operation are reduced.

A method for improving the selectivity of a supported highly selective epoxidation catalyst comprising silver in a quantity of at most 0.19 g per m<2> surface area of the support, which method comprises - contacting the catalyst, or a precursor of the catalyst comprising the silver in cationic form, with a feed comprising oxygen at a catalyst temperature above 250 DEG C for a duration of up to 150 hours, and - subsequently decreasing the catalyst temperature to a value of at most 250 DEG C; and a process for the epoxidation of an olefin, which process comprises - contacting a supported highly selective epoxidation catalyst comprising silver in a quantity of at most 0.19 g per m<2> surface area of the support, or a precursor of the catalyst comprising the silver in cationic form, with a feed comprising oxygen at a catalyst temperature above 250 DEG C for a duration of up to 150 hours, and - subsequently decreasing the catalyst temperature to a value of at most 250 DEG C and contacting the catalyst with the feed comprising the olefin and oxygen.