Abstract: A purification method for obtaining high-purity PMDA. The method controls temperatures of cyclone separators in a series to separate PMDA and other by-products of different sublimation temperatures. High-purity PMDA is collected in the first cyclone separator, and no other purification steps are needed.

Abstract: A purification method for obtaining high-purity PMDA. The method controls temperatures of cyclone separators in a series to separate PMDA and other by-products of different sublimation temperatures. High-purity PMDA is collected in the first cyclone separator, and no other purification steps are needed.

Abstract: The present invention relates to a process for preparing pyromellitic dianhydride via an oxidation in gas phase under normal pressure. The process is characterized in that a catalyst system is used, which catalyst system comprises a catalyst which is a mixture of vanadium and tungsten oxides; a catalyst support comprising rutile and at least one material selected from the group consisting of tungsten carbide, silicon carbide and a mixture thereof; and a cocatalyst comprising oxides of manganese, antimony, bismuth, phosphorus, copper, aluminum, titanium or a mixture thereof, an oxide of an element of the VIIIB group of the periodic table, and an oxide of an alkali metal and/or alkaline earth metal. In this process, pyromellitic dianhydride is produced from a feedstream containing 1,2,4,5-tetraalkylbenzene in a gas flow rate of 4,000.about.12,000 hr.sup.-1 via a selective oxidation at 300.about.450.degree. C. in the presence of air which acts as an oxidant.

Abstract: A simple and single step process for producing caprolactam comprising reacting 5-formylvaleric acid or an ester thereof in a solvent of water and/or an alcohol with hydrogen and ammonia in the presence of a noble metal catalyst supported by a carrier at 80.degree. to 300.degree. C. under a pressure of 10 to 120 atm, whereby amination, acidification, dehydration and cyclization occur to obtain caprolactam.

Abstract: A one-step process for selective production of methyl isobutyl ketone includes reacting in the vapor/liquid phase acetone and hydrogen at a temperature of about 100.degree. to 300.degree. C. and a pressure of about 100 to 1000 psig, in the presence of a modified ZSM-5 catalyst having a molar ratio of SiO.sub.2 /Al.sub.2 O.sub.3 from about 20:1 to 680:1, the catalyst being prepared by treating a ZSM-5 zeolite with an organic acid having a pKa of 2 to 5, ion-exchanging or impregnating the ZSM-5 zeolite with a cation selected from the group consisting of palladium cation, platinum cation, copper cation and nickel cation, and activating the resultant catalyst in a reducing atmosphere.

Abstract: The present invention relates to a method for the production of N-vinyl-2-pyrrolidone with high selectivity. The method is characterized in subjecting 2-pyrrolidone and acetylene to vinylation by using hydroxy end-capped ether oligomers having a molecular weight less than 1000 or linear diols having at least 4 carbon atoms as co-catalysts under the catalyzation of alkali metal salts. At a vinylation temperature of 100.degree.-200 .degree. C., a reaction pressure of 7.5-30 atm and a reaction time period of 3-20 hours, N-vinyl-2-pyrrolidones are obtained with yields above 90%.

Abstract: A method of making caprolactam from aminohexanoic acid or aminohexanoate ester comprising the steps of: (a) obtaining a reactor containing at least one catalyst, the catalyst being a metal oxide having acid-base-paired active sites; (b) charging a reaction feed into the reactor, the reaction feed containing a reactant, which is either amniohexanoic acid or C.sub.1 to C.sub.12 alkyl aminohexanoate ester, and a solvent; (c) reacting the reaction feed at a reaction temperature between 140.degree. and 300.degree. C. and a reaction pressure between 10 and 100 atm, to form a product stream; and (d) separating caprolactam from the product stream.

Abstract: The present invention relates to a method for the production of N-vinyl-2-pyrrolidone by gas-phase reaction at atmospheric pressure. The method is characterized in that a gas-phase reaction is conducted by using N-.beta.-Hydroxyethyl-2-Pyrrolidones serving as raw materials, at a temperature of 300.degree.-450.degree. C., a space velocity of 500-4500 hr.sup.-1 in the presence of a mixed oxide of group IV elements, or an oxide of group IV elements, which has been modified by group I or group II elements.

Abstract: A method for preparing ester end-capped polyalkylene ether is disclosed. Cyclic ether monomers are subjected to ring-opening polymerzation at a temperature of 20.degree.-80.degree. C. and a pressure of 0-10 atm in the presence of a solid acid serving as catalyst and a mixture of acid and acid anhydride serving as a promoter. The solid acid is an oxide of group III and group IV elements and has been modified by sulfuric acid, ammonium sulfate or ammonium sulfite.

Abstract: A method for preparing ester end-capped polyalkylene ether is disclosed. Cyclic ether monomers are subjected to ring-opening polymerization at a temperature of 10.degree.-80.degree. C. and a pressure of 0-10 atm in the presence of a solid acid of a mixed oxide of group III and group IV elements serving as catalyst and a mixture of acid and acid anhydride serving as molecular weight moidifier. The group III and group IV elements used should have a Ho index of +3.0 to -10.0.