Abstract: A method for synthesizing trioxane by heating and reacting an aqueous formaldehyde solution in the presence of a heteropolyacid. As the heteropolyacid, there is preferably used one that contains, as a coordinating element or coordinating elements, W, Mo, V or Nb alone or two or more of them.

Abstract: A process for recovering trioxane from an aqueous solution containing trioxane and triethylamine by the distillation separation process which comprises feeding an aqueous solution containing trioxane and triethylamine to the first distillation column, distilling out triethylamine, trioxane and water from the column top of the first distillation column, withdrawing an aqueous solution containing the major part of the trioxane present in the fed solution from the column bottom of the first distillation column, feeding the withdrawn solution to the second distillation column and taking out the substantially whole quantity of the trioxane fed to the second distillation column from the column top of the second distillation column.

Abstract: An oxymethylene copolymer produced from trioxane, a cyclic ether and/or a cyclic formal in the presence of a cationic polymerization catalyst is contacted with a deactivating agent for the catalyst in the state of gas phase at a temperature of 160.degree. C. or lower to deactivate the cationic polymerization catalyst rapidly and completely without causing degradation of the copolymer produced.

Abstract: A shaped composite adsorbent made of a shaped porous material of a skin-core structure comprising a powdery ion-exchange type adsorbent and an ionic group-containing acrylonitrile polymer and wherein said shaped porous material has a semi-permeable skin layer of 0.01 to 1.mu. in thickness and a void volume rate of 50 to 90%, which is capable of adsorbing solutes present at low concentration with high selectivity and high yield. The shaped composite adsorbent of the present invention can be obtained by a process comprising dissolving an ionic group-containing acrylonitrile polymer in and dispersing a powdery ion exchange type adsorbent in an inorganic solvent for said acrylonitrile polymer, extruding the resultant into a coagulating liquid bath to effect coagulation-shaping thereof.

Abstract: A method for synthesizing trioxane by heating and reacting an aqueous formaldehyde solution in the presence of a heteropolyacid. As the heteropolyacid, there is preferably used one that contains, as a coordinating element or coordinating elements, W, Mo, V or Nb alone or two or more of them.

Abstract: In a process for separating trioxane by a continuous distillation which comprises extracting, with benzene, the trioxane-containing distillate obtainable by heating an aqueous solution of formaldehyde, feeding the trioxane-containing benzene solution into a distillation column as a starting material, distilling out the benzene from the column top and withdrawing the trioxane from the column bottom, a process for separating trioxane which comprises retaining the concentration of trioxane X in the liquid composition at the starting material feeding plate of the distillation column (% by weight of trioxane based on the total liquid composition at the feeding plate) in the range satisfying the following relationship: ##EQU1## wherein R is reflux ratio, and .gamma. is a parameter defined by the following equation: ##EQU2## wherein q is the proportion of liquid part in the fed starting material as expressed in terms of ratio by weight and C (%) is the concentration of trioxane in the fed starting material.

Abstract: Pseudo-boehmite having a bulk density of about 0.05 to 0.2 g/cc, an oil absorption of about 2.5 to 6.0 cc/g, a pore volume of about 2.0 to 7.0 cc/g over a pore diameter range of 176.mu. to 0.0035.mu. and a specific surface area of about 200 to 500 m.sup.2 /g, and a process for producing the same; useful as a filler, an absorbent, a catalyst, a filtering agent and a base material for composites; prepared by mixing alkali aluminate and halohydrin together at a low temperature, heating for reaction the resulting mixture, cooling the reacting solution, separating the resulting precipitate by filtration and, if desired subjecting the precipitate to washing with an organic solvent followed by drying.

Abstract: A magnesia cement composition comprising active magnesia, magnesium sulfate, and pulp or a mixture of pulp and fibrous glass. When hardened, this composition yields a crack-free low-shrinkage material. Valuable composite boards are obtained by lamination from the hardened composition and core materials such as cellular concrete, plywood, plastic foam, gypsum plaster board, and cemented excelsior board.