In a method for producing an aliphatic carboxylic acid ester by reacting an aliphatic carboxylic acid having from 1 to 5 carbon atoms and an olefin having from 2 to 4 carbon atoms in a gas phase by use of a solid acid catalyst, a solid acid catalyst in which a heteropolyacid or a salt thereof is supported on a silica carrier obtainable by kneading fumed silica obtained by a combustion method, silica gel obtained by a gel method, and colloidal silica obtained by a sol-gel method or a water glass method, molding the resulting kneaded product, and calcining the resulting molded body, is used.

A method for producing the silica carrier which includes kneading fumed silica obtained by a combustion method, silica gel obtained by a gel method, and colloidal silica obtained by a sol-gel method or a water glass method, molding the resulting kneaded product, and calcining the resulting molded body. The silica carrier has, in the measurement of pore size distribution, mesopores with a pore size of 2 to 50 nm and macropores with a pore size of more than 50 nm and 1,000 nm or less.

An embodiment of the present invention provides a method for manufacturing multi-wall carbon nanotubes, the method comprising the steps of: (a) dissolving a metal precursor in a solvent to prepare a precursor solution; (b) perform thermal decomposition while spraying the precursor solution into a reactor, thereby forming a catalyst powder; and (c) introducing the catalyst powder into a fluidized-bed reactor heated to 600-900 C. and spraying a carbon-based gas and a carrier gas to synthesize multi-wall carbon nanotubes from the catalyst powder, wherein steps (a) to (c) are performed in a continuous type and wherein the catalyst powder contains metal components according to equation 1 below. <Equation 1> Ma:Mb=x:y, wherein Ma represents at least two metals selected from Fe, Ni, Co, Mn, Cr, Mo, V, W, Sn, and Cu; Mb represents at least one metal selected from Mg, Al, Si, and Zr; x and y each represent the molar ratio of Ma and Mb; and x+y=10, 2.0x7.5, and 2.5y8.0.

Oxidative dehydrogenation catalysts comprising MoVNbTeO having improved consistency of composition and a 25% conversion of ethylene at less than 420 C. and a selectivity to ethylene above 95% are prepared by treating the catalyst precursor with H.sub.2O.sub.2 in an amount equivalent to 0.30-2.8 mL H.sub.2O.sub.2 of a 30% solution per gram of catalyst precursor prior to calcining.

A method for treating reverse osmosis concentrated water, comprises adding precipitant and oxidant to reverse osmosis concentrated water for treatment, filtering to obtain clear liquid, and adding catalyst for water treatment to clear liquid for catalytic oxidation to obtain a first-stage treated water. Optionally, the liquid may be subjected after catalytic oxidation to an adsorption treatment; performing reverse osmosis treatment on first-stage treated water to obtain second-stage reverse osmosis product water and second-stage reverse osmosis concentrated water; and adding oxidant to second-stage reverse osmosis concentrated water for oxidation treatment to obtain directly discharged effluent water. The obtaining of effluent water may further comprise subjecting liquid after oxidation treatment to adsorption treatment. The above method can recycle 75-85 wt % of water, and operates easily. Thereby, improvement to overall utilization rate of water, and treatment of little remaining water is met to effluent standard for reduction of environmental pollution and economic investment.

The present invention relates to a mixed oxide of aluminium, of zirconium, of cerium, of lanthanum and optionally of at least one rare-earth metal other than cerium and lanthanum that makes it possible to prepare a catalyst that retains, after severe ageing, a good thermal stability and a good catalytic activity. The invention also relates to the process for preparing this mixed oxide and also to a process for treating exhaust gases from internal combustion engines using a catalyst prepared from this mixed oxide.

A catalyst fibrous structure having a catalyst metal carried on a fibrous structure, wherein (a) a Log differential micropore volume distribution curve thereof obtained by measurement using a mercury intrusion technique has a peak having a maximum micropore diameter in the range of from 0.1 m to 100 m: (b) a Log, differential micropore volume at the peak is 0.5 mL/g or more; and (c) an amount of a catalyst metal compound and a binder carried per unit volume is 0.05 g/mL or more. Also, a production method for producing a catalyst fibrous structure.

A catalyst for a selective conversion of hydrocarbons. The catalyst includes a first component selected from the group consisting of Group VIII noble metals and mixtures thereof, a second component selected from the group consisting of alkali metals or alkaline-earth metals and mixtures thereof, and a third component selected from the group consisting of tin, germanium, lead, indium, gallium, thallium and mixtures thereof. The catalyst is a support formed as a spherical catalyst particle with an average pore diameter between 200 to 350 Angstroms, a porosity of at least 75% and an apparent bulk density between 0.60 and 0.3 g/cc. Also, a process of using such a catalyst for a selective hydrocarbon conversion reaction and a process for regenerating such a catalyst by removing coke from same.

A catalyst for a selective conversion of hydrocarbons. The catalyst includes a first component selected from the group consisting of Group VIII noble metals and mixtures thereof, a second component selected from the group consisting of alkali metals or alkaline-earth metals and mixtures thereof, and a third component selected from the group consisting of tin, germanium, lead, indium, gallium, thallium and mixtures thereof. The catalyst is a support formed as a spherical catalyst particle with a median diameter between 1.6 mm and 2.5 mm and an apparent bulk density between 0.6 and 0.3 g/cc. Also a process of using such a catalyst for a selective hydrocarbon conversion reaction and a process for regenerating such a catalyst by removing coke from same.

The present disclosure relates to the technical field of fine chemical engineering, and particularly discloses a stepwise solidus synthesis method for a micro-mesoporous calcium aluminate catalyst, comprising: mixing a calcium oxide-based powder with an alumina-based powder and an adhesion pore-enlarging agent; pelleting and molding the mixture; pyrolyzing and coking the pelleted and molded product in a rotary kiln reactor under the conditions including an outlet reaction temperature of 300 C.500 C. and a residence time of 0.23.5 h; and subsequently carrying out a solidus reaction in an internal heating rotary kiln reactor under the conditions including an outlet reaction temperature of 900 C.1,500 C. and a residence time of 0.15 h to produce calcium aluminate; decomposing and gasifying the pyrolyzed char in the calcium aluminate to promote the formation of pores, thereby producing micro-mesoporous calcium aluminate catalyst; wherein the weight ratio between the calcium oxide-based powder and the alumina-based powder is within a range of 12:(215), the added amount of the adhesion pore-enlarging agent accounts for 0.115% by weight of a total amount of the calcium oxide-based powder and alumina-based powder; wherein the weight of the calcium oxide-based powder is calculated based on calcium oxide, and the weight of the alumina-based powder is calculated based on alumina. The calcium aluminate catalyst prepared with the method provided by the present disclosure has advantages of large specific surface area, low density and high strength.