Air Products and Chemicals, Inc.

Philip J Cook

Michael S Chen

Harold H Gunardson

Melinda B Ulrich

The present invention is an improvement to the conventional process for the production of phthalic anhydride. In particular, the present invention enables the crude phthalic anhydride product to be recovered in a more efficient manner.

Elevated pressure phthalic anhydride process

A process is provided for purifying argon gas, especially an argon gas stream obtained by cryogenically separating air, wherein the argon gas is heated and compressed, and then permeated through a solid electrolyte membrane selective to the permeation of oxygen over other components of the gas, and removing oxygen from the argon by selective permeation of oxygen through the membrane. The purified argon can then be distilled to remove other components such as nitrogen.

Process for removing oxygen from crude argon

The present invention relates to an improved process for the reliquefaction of boil-off gas containing up to 10% nitrogen resulting from the evaporation of liquefied natural gas (LNG) contained in a storage vessel. In the process, a closed-loop refrigeration cycle is utilized wherein an isenthalpically expanded stream is warmed against an initially cooled boil-off stream. The boil-off LNG stream is initially cooled by indirect heat exchange with an isentropically expanded refrigerant stream.

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Schnecksville, PA, United States of America

Philip J Cook