The object of the present invention is to provide an exhaust gas purifying catalyst that can achieve high purification performance while suppressing H.sub.2S emissions. The object is solved by an exhaust gas purifying catalyst in which the top layer of a catalyst coating layer comprises a ceria-zirconia composite oxide having a pyrochlore-type ordered array structure, in which the ceria-zirconia composite oxide contains at least one additional element selected from the group consisting of praseodymium, lanthanum, and yttrium at 0.5 to 5.0 mol % in relation to the total cation amount, and the molar ratio of (cerium+additional element):(zirconium) is within the range from 43:57 to 48:52.

Disclosed is a process for the preparation of 1,3,3,3-tetrafluoropropene, comprising: (a) a compound having the formula CF.sub.3-xCl.sub.xCHClCHF.sub.2-yCl.sub.y and in the presence of a compound catalyst, undergoes, through n serially-connected reactors, gas-phase fluorination with hydrogen fluoride, producing 1,2,3-trichloro-1,1,3-trifluoropropane, and 1,2-dichloro-1,1,3,3-tetrafluoropropane; in said formula, x=1, 2 or 3; y=1 or 2, and 3≦x+y≦5; (b) 1,2,3-trichloro-1,1,3-trifluoropropane, and 1,2-dichloro-1,1,3,3-tetrafluoropropane undergo, in the presence of a dehalogenation catalyst, gas-phase dehalogenation with hydrogen, producing 3-chloro-1,3,3-trifluoropropene, and 1,1,3,3-tetrafluoropropene; (c) 3-chloro-1,3,3-trifluoropropene and 1,1,3,3-tetrafluoropropene undergo, in the presence of a fluorination catalyst, gas-phase fluorination with hydrogen fluoride, producing 1,3,3,3-tetrafluoropropene. The present invention is primarily used to produce 1,3,3,3-tetrafluoropropene.

Disclosed is a process for the preparation of 1,3,3,3-tetrafluoropropene, comprising: (a) a compound having the formula CF.sub.3-xCl.sub.xCHClCHF.sub.2-yCl.sub.y and in the presence of a compound catalyst, undergoes, through n serially-connected reactors, gas-phase fluorination with hydrogen fluoride, producing 1,2,3-trichloro-1,1,3-trifluoropropane, and 1,2-dichloro-1,1,3,3-tetrafluoropropane; in said formula, x=1, 2 or 3; y=1 or 2, and 3≦x+y≦5; (b) 1,2,3-trichloro-1,1,3-trifluoropropane, and 1,2-dichloro-1,1,3,3-tetrafluoropropane undergo, in the presence of a dehalogenation catalyst, gas-phase dehalogenation with hydrogen, producing 3-chloro-1,3,3-trifluoropropene, and 1,1,3,3-tetrafluoropropene; (c) 3-chloro-1,3,3-trifluoropropene and 1,1,3,3-tetrafluoropropene undergo, in the presence of a fluorination catalyst, gas-phase fluorination with hydrogen fluoride, producing 1,3,3,3-tetrafluoropropene. The present invention is primarily used to produce 1,3,3,3-tetrafluoropropene.

Disclosed are a catalyst for oxidative coupling reaction of methane, a method for preparing the same, and a method for oxidative coupling reaction of methane using the same. The catalyst includes a mixed metal oxide, which is a mixed oxide of metals including sodium (Na), tungsten (W), manganese (Mn), barium (Ba) and titanium (Ti). It is possible to obtain paraffins, such as ethane and propane, and olefins, such as ethylene and propylene, with high efficiency through the method for oxidative coupling reaction of methane using the catalyst.

Disclosed are a catalyst for oxidative coupling reaction of methane, a method for preparing the same, and a method for oxidative coupling reaction of methane using the same. The catalyst includes a mixed metal oxide, which is a mixed oxide of metals including sodium (Na), tungsten (W), manganese (Mn), barium (Ba) and titanium (Ti). It is possible to obtain paraffins, such as ethane and propane, and olefins, such as ethylene and propylene, with high efficiency through the method for oxidative coupling reaction of methane using the catalyst.

Disclosed is a process for the preparation of 2,3,3,3-tetrafluoropropene, comprising the following two reaction steps: a. a compound having the formula CF.sub.3-xCl.sub.xCF.sub.2-yCl.sub.yCH.sub.2Cl undergoes gas-phase fluorination with hydrogen fluoride through n serially-connected reaction vessels in the presence of a compound catalyst producing 2,3-dichloro-1,1,1,2-tetrafluoropropane, 1,2,3-trichloro-1,1,2-trifluoropropane, and 1,3-dichloro-1,1,2,2-tetrafluoropropane; in said formula, x=1, 2, 3, y=1, 2, and 3≦x+y≦5; b. the 2,3-dichloro-1,1,1,2-tetrafluoropropane, 1,2,3-trichloro-1,1,2-trifluoropropane, and 1,3-dichloro-1,1,2,2-tetrafluoropropane undergo gas-phase dehalogenation with hydrogen in the presence of a dehalogenation catalyst, producing 2,3,3,3-tetrafluoropropene and 3-chloro-2,3,3-trifluoropropene, then separation and refining are performed, producing 2,3,3,3-tetrafluoropropene. The present invention is primarily used to produce 2,3,3,3-tetrafluoropropene.

Disclosed is a process for the preparation of 2,3,3,3-tetrafluoropropene, comprising the following two reaction steps: a. a compound having the formula CF.sub.3-xCl.sub.xCF.sub.2-yCl.sub.yCH.sub.2Cl undergoes gas-phase fluorination with hydrogen fluoride through n serially-connected reaction vessels in the presence of a compound catalyst producing 2,3-dichloro-1,1,1,2-tetrafluoropropane, 1,2,3-trichloro-1,1,2-trifluoropropane, and 1,3-dichloro-1,1,2,2-tetrafluoropropane; in said formula, x=1, 2, 3, y=1, 2, and 3≦x+y≦5; b. the 2,3-dichloro-1,1,1,2-tetrafluoropropane, 1,2,3-trichloro-1,1,2-trifluoropropane, and 1,3-dichloro-1,1,2,2-tetrafluoropropane undergo gas-phase dehalogenation with hydrogen in the presence of a dehalogenation catalyst, producing 2,3,3,3-tetrafluoropropene and 3-chloro-2,3,3-trifluoropropene, then separation and refining are performed, producing 2,3,3,3-tetrafluoropropene. The present invention is primarily used to produce 2,3,3,3-tetrafluoropropene.

A catalyst composition includes a metal catalyst dispersed in a molten eutectic mixture of alkali metal or alkaline earth metal carbonates or hydroxides. A process for the catalytic cracking of hydrocarbons includes contacting in a reactor system a carbon-containing feedstock with at least one catalyst in the presence of oxygen to generate olefinic and/or aromatic compounds; and collecting the olefinic and/or aromatic compounds; wherein: the at least one catalyst includes a metal catalyst dispersed in a molten eutectic mixture of alkali metal or alkaline earth metal carbonates or hydroxides. A process for preparing the catalyst includes mixing metal catalyst precursors selected from transition metal compounds and rare-earth metal compounds and a eutectic mixture of alkali metal or alkaline earth metal carbonates or hydroxides and heating it. A use of the catalyst in the catalytic cracking process of hydrocarbons.

A catalyst composition includes a metal catalyst dispersed in a molten eutectic mixture of alkali metal or alkaline earth metal carbonates or hydroxides. A process for the catalytic cracking of hydrocarbons includes contacting in a reactor system a carbon-containing feedstock with at least one catalyst in the presence of oxygen to generate olefinic and/or aromatic compounds; and collecting the olefinic and/or aromatic compounds; wherein: the at least one catalyst includes a metal catalyst dispersed in a molten eutectic mixture of alkali metal or alkaline earth metal carbonates or hydroxides. A process for preparing the catalyst includes mixing metal catalyst precursors selected from transition metal compounds and rare-earth metal compounds and a eutectic mixture of alkali metal or alkaline earth metal carbonates or hydroxides and heating it. A use of the catalyst in the catalytic cracking process of hydrocarbons.

An exhaust system for an internal combustion engine, the exhaust system comprising, a lean NO.sub.x trap (LNT), a wall flow monolithic substrate having a NO.sub.x storage and reduction zone thereon, the wall flow monolithic substrate having a pre-coated porosity of 40% or greater, the NO.sub.x storage and reduction zone comprising a platinum group metal loaded on a first support, the first support comprising one or more alkaline earth metal compounds, a mixed magnesium/aluminium oxide, cerium oxide, and at least one base metal oxide selected the group consisting of copper oxide, manganese oxide, iron oxide and zinc oxide.