Nippon Shokubai Kagaku Kogyo Co., Ltd.

Michito Okane

Takahisa Sato

Masao Baba

Hideo Suzuki

Masao Nakano

Takezo Sonoda

In a process for producing acrylic acid which comprises contacting with water an acrylic acid-containing reaction product gas which has been obtained by the catalytic vapor phase oxidation of an olefinic compound of a general formula, CH.sub.2 .dbd.CHX, wherein X represents at least one group selected from the group consisting of CH.sub.3 and CHO, with a molecular oxygen-containing gas thereby collecting the acrylic acid in the form of an aqueous solution, separating the acrylic acid from the aqueous solution, and refining the thus separated acrylic acid, the improvement comprising a step of subjecting the bottom liquor of a rectification tower for acrylic acid to a decomposition evaporation and a step of subjecting the evaporation residue having a composition of 1-25 wt % of acrylic acid, 9-49 wt % of acrylic acid dimer, wherein total amount of the acrylic acid and its dimer is in the range of 10-50 wt %, and correspondingly 90-50 wt % of other matters to an extraction with water to separate the acrylic acid, its dimer and hydroquinone by the extraction.

Process for preparing and recovering acrylic acid

In a process for desulfurizing hydrogen sulfide-containing gases by contacting a hydrogen sulfide-containing gas with an alkaline aqueous solution containing a naphthoquinonesulfonate to effect absorption of hydrogen sulfide by said aqueous solution and subjecting the effluent to catalytic oxidation by a molecular oxygen-containing gas to separate out sulfur, an improvement which comprises (a) carrying out the absorption of hydrogen sulfide by using a liquid absorbent having a pH value adjusted by means of ammonia to 8 to 10 and containing as catalyst components a naphthoquinonesulfonate and a variable valent metal compound, (b) carrying out the catalytic oxidation of the effluent containing absorbed therein hydrogen sulfide by means of a molecular oxygen-containing gas as to lower the concentration of hydrosulfide ion in the effluent to 70 ppm or less and (c) recirculating the said liquid absorbent or effluent to the contact with the said hydrogen sulfide-containing gas.

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Himeji, Japan

Michito Okane