Abstract: A method for producing tert-butyl alcohol, including (i) a step of feeding a raw material liquid including isobutylene and water, to a reactor having a cation exchange resin, and (ii) a step of producing a reaction product including tert-butyl alcohol, by hydration reaction of isobutylene in the reactor, in which, in step (ii), the average superficial linear velocity of the raw material liquid, as calculated in the following expression (I), is 5 m/hour or more, Average linear velocity of raw material liquid (m/hour)=Volume flow rate of raw material liquid (m3/hour)/Cross-sectional area of reactor (m2)??(I), and the volume of an aqueous phase (Vw) in a fluid (fluid A) to the total volume of the fluid A in the reactor is 4 to 12% by volume.

Abstract: Provided is a method for separating water-containing crystals, the method including: a step of generating water-containing crystals from a mixed liquid including water, acetic acid, and methacrylic acid; and a step of separating the crystals, in which the proportion by mass of methacrylic acid with respect to the total mass of water, acetic acid, and methacrylic acid in the mixed liquid is 0.09% by mass or more and less than 0.60% by mass.

Abstract: The purpose of the present invention is to provide a method for manufacturing a porous hollow fiber membrane in which the amount of a hypochlorite used during pore forming agent removal treatment can be reduced and the facilities cost can be minimized, and in which the post-treatment waste liquid can be readily treated. This method for manufacturing a porous hollow fiber membrane has: coagulating a membrane forming material liquid containing a membrane forming resin and a pore forming agent by a coagulating liquid, to thereby form a porous hollow fiber membrane precursor; and removing the porous hollow fiber membrane precursor impregnated at least with a liquid into contact with ozone gas in a vapor phase, to thereby decompose and remove the pore forming agent present in the membrane.