A photocatalyst includes a composite fiber having at least two crystalline semi-conductors that provide a heterojunction structure in the composite fiber.

Mixed metal oxide catalysts having an amorphous content of not less than 40 wt. % are prepared by calcining the catalyst precursor fully or partially enclosed by a porous material having a melting temperature greater than 600 C. in an inert container including heating the catalyst precursor at a rate from 0.5 to 10 C. per minute from room temperature to a temperature from 370 C. to 540 C. under a stream of pre heated gas chosen from steam and inert gas and mixtures thereof at a pressure of greater than or equal to 1 psig having a temperature from 300 C. to 540 C. and holding the catalyst precursor at that temperature for at least 2 hours and cooling the catalyst precursor to room temperature.

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.

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 and treating the resulting catalyst with the equivalent amount of peroxide after calcining.

Processes and associated reaction systems for the oxidative dehydrogenation of ethane are provided. In particular, a process is provided that comprises supplying a feed gas comprising ethane and oxygen to a multitubular fixed-bed reactor and allowing the ethane and oxygen to react in the presence of an oxidative dehydrogenation catalyst to yield a reactor effluent comprising ethylene; and supplying a coolant to an interior shell space of the multitubular fixed-bed reactor in a flow pattern that is co-current with the flow of the feed gas through reactor.

A method for producing a target compound includes distributing a feed mixture at a temperature in a first temperature range to a plurality of parallel reaction tubes of a shell-and-tube reactor, and subjecting the feed mixture in first tube sections of the reaction tubes to heating to a temperature in a second temperature range and in second tube sections of the reaction tubes arranged downstream of the first tube sections to oxidative catalytic conversion using one or more catalysts. A gas mixture flowing out of the second tube sections is brought into contact in third tube sections arranged downstream of the second tube sections with a catalyst which has a volumetric activity below the highest volumetric activity of the one or the plurality of catalysts arranged in the second tube sections. A gas mixture from the third tube sections is withdrawn from the shell-and-tube reactor without further catalytic conversion.

A process for producing a target compound includes forming a feed mixture containing at least one reactant compound. The feed mixture is distributed to parallel reaction tubes of one or more shell-and-tube reactors and subjected to oxidative catalytic conversion in the reaction tubes. Steam is added to the feed mixture in an amount such that a steam fraction of the feed mixture is 5 to 95 vol %, oxygen is added to the feed mixture in the form of a fluid containing at least 95 vol % oxygen, and the oxidative catalytic conversion is carried out using one or more catalysts containing the metals molybdenum, vanadium, niobium and optionally tellurium.

A method for producing a target compound, includes distributing feed mixture at a temperature in a first temperature range to a plurality of parallel reaction tubes of a shell-and-tube reactor. The method further includes subjecting the feed mixture in first tube sections of the reaction tubes to heating to a temperature in a second temperature range, and in second tube sections of the reaction tubes arranged downstream of the first tube sections to oxidative catalytic conversion using one or more catalysts arranged in the second tube sections. The heating is performed, at least in part, using a catalyst arranged in the first tube sections and having a light-off temperature in the first temperature range.

Catalysts and Methods for large-scale production of the catalysts are provided. An exemplary catalyst composition includes molybdenum, vanadium, tellurium, niobium, oxygen. In the catalyst composition, the molar ratio of molybdenum to vanadium is from 1:0.05 to 1:0.60, the molar ratio of molybdenum to tellurium is from 1:0.01 to 1:0.30, and the molar ratio of molybdenum to niobium is from 1:0.01 to 1:0.40. Oxygen is present at least in an amount to satisfy the valency of any present metal oxides, and composition includes less than 1.0 wt. % of sulfur.

A method of producing and separating an alkene, such as ethylene, from an alkane, such as ethane. The method comprises subjecting a feedstock comprising ethane to oxidative dehydrogenation to produce an ethylene stream. The ethylene stream is passed through a membrane separation unit to separate the ethylene from unreacted ethane in the ethylene stream. The ethylene is recovered from the membrane separation unit. A system configured to produce ethylene is also disclosed. The system comprises at least one ODH reactor, a heat management unit coupled to the at least one ODH reactor, and at least one membrane separation unit comprising at least one membrane. The ODH reactor is configured to convert ethane to ethylene. The heat management unit is configured to reduce a temperature of the ethylene. The at least one membrane is configured to separate the ethylene from unreacted ethane.