A PROCESS FOR SWEETENING SOUR GAS BY DIRECT THERMOLYSIS OF HYDROGEN SULFIDE

ABOUT 25 PERCENT OF U.S. NATURAL GAS RESERVES ARE RENDERED UNUSABLE BY HYDROGEN SULFIDE (H2S) CONTAMINATION; IF THIS SOUR GAS WERE TREATED, OR "SWEETENED", THE RESERVES COULD PROVIDE ENOUGH NATURAL GAS TO MEET THE ANNUAL NATIONAL DEMAND FOR 6 YEARS. CURRENT SOUR-GAS SWEETENING PROCESSES PRODUCE TOXIC AND ENVIRONMENTALLY UNACCEPTABLE EMISSIONS, AND THEY WILL NOT BE ADEQUATE FOR FULLY UTILIZING THE NATION'S SOUR-GAS RESERVES AS INCREASINGLY STRINGENT REGULATIONS ARE ESTABLISHED. THE PLANNED RESEARCH AIMS TO DEVELOP A NOVEL AND EFFICIENT MEMBRANE-BASED PROCESS THAT OVERCOMES THE PROBLEMS ASSOCIATED WITH THE AVAILABLE SOUR-GAS SWEETENING PROCESSES BY DIRECTLY THERMOLYZING H2S, YIELDING TWO ENVIRONMENTALLY BENIGN BYPRODUCTS: ELEMENTAL SULFUR AND WATER. PREVIOUS STUDIES CONDUCTED BY THE RESEARCHERS FOR APPLICATIONS OTHER THAN GAS SWEETENING HAVE DEMONSTRATED THE FEASIBILITY OF THE BASIC CONCEPT OF H2S THERMOLYSIS WITH A METAL-MEMBRANE REACTOR. PHASE I OF THIS PROJECT IS DIRECTED TOWARD DETERMINING (1) THE RATE-LIMITING STEP FOR H2S REMOVAL, (2) WHETHER COKING OF THE MEMBRANE WILL RESULT IN UNACCEPTABLE METHANE LOSSES, AND (3) WHETHER THERE WILL BE A NEED FOR MEMBRANE OPTIMIZATION, SECONDARY PROCESSING, OR BOTH. DETERMINATION OF THESE FACTORS WILL ENABLE RESEARCHERS TO ESTABLISH A MEMBRANE REACTOR DESIGN ON WHICH TO BASE PRELIMINARY ENGINEERING AND ECONOMIC ANALYSIS. PHASE II WILL EVALUATE MEMBRANE LIFETIME, DESIGN AND CONSTRUCT A PRE-PROTOTYPE MEMBRANE REACTOR, AND DEMONSTRATE THE PROCESS BY USING A FEED STREAM THAT SIMULATES A TYPICAL SOUR-GAS COMPOSITION. IT IS ANTICIPATED THAT THIS PLAN WILL SCALE ECONOMICALLY OVER THE FULL VOLUME-RANGE OF SOUR-GAS STREAMS.