Zeolite Membrane Reactor for Pre-Combustion Carbon Dioxide Capture (Final Scientific/Technical Report)
Water-gas shift (WGS) reaction followed by carbon dioxide (CO2) separation is a critical step in the integrated gasification combined cycle (IGCC) process for fossil-fuel-fired electrical power generation with CO2 capture. To intensify the IGCC process hydrogen-permselective zeolite membrane reactor offers promise to replace the conventional energy-intensive fixed-bed reactors and solvent-based CO2 capture units. The objectives of this project were to develop a bench-scale zeolite membrane reactor (total membrane area: 932 cm2 for a 21-tube membrane bundle) for the water-gas-shift reaction of raw syngas from an oxygen-blown coal-gasifier for H2 production with simultaneous CO2 separation at the capability of about 2 kilograms H2 per day (equivalent to 2 kW IGCC power plant) and to demonstrate significant progress toward achieving overall performance goal of 90% CO2 capture rate with 95% CO2 purity at the cost of electricity 30% less than the baseline carbon capture approaches. This report summarizes results obtained in this project on scaling up the zeolite membrane reactor by a factor of 200 in membrane area, tests of the bench-scale zeolite membrane reactor for the water-gas-shift reaction at high temperature and high-pressure, and techno-economic analysis of the integration of the zeolite membrane reactor in IGCC power plant for the electrical generation with CO2 capture. With effective pore modification by catalytic cracking deposition of MDES (methyldiethoxysilane), fabrication of MFI-type zeolite membranes was successfully scaled-up from a lab-scale disk type to bench-scale multiple-tube bundles on low-cost alumina supports. A Co-Mo based sour shift catalyst was evaluated and used in the zeolite membrane reactors for water-gas-shift reaction. The reaction kinetic and gas-permeation equations were developed and employed in mathematic models to guide/predict experiments/performance of zeolite membrane reactors for water-gas shift reaction. Multiple-tube zeolite membrane bundles and reactors were designed, fabricated and tested for gas separation and water-gas-shift reactions with real raw syngas from a coal-fired gasifier operated at high temperature and pressure. The zeolite membrane reactors demonstrated good long-term thermal and chemical stability and constant H2 permeance (>300 GPU) together with a Knudsen selectivity (~4.7) for H2 over CO2 in the field test (cumulative time >28 hours) with high-sulfur coal-derived syngas. The zeolite-membrane-reactor integrated IGCC process was designed using the performance experimentally measured by the University of Cincinnati team with a single-tube zeolite membrane reactor that offers a CO conversion >98% with more than 90% of CO2 and H2 captured. With the above integrative approaches, a techno-economic analysis for a cost-benefit comparison was performed to uncover features that determine the power output, capital expenditure, operating expenditure, cost of electricity and cost of CO2 capture in a 550-MW zeolite-membrane-reactor integrated IGCC process. The integration of the zeolite membrane reactor in IGCC could provide a significant reduction of 80% and 27% in the power consumption for Selexol™ Acid Gas Removal and CO2 compression, respectively, which lowers the total auxiliary power consumption by 12.5%. However, the low pressure required at permeate stream for maintaining the driving force of hydrogen permeation through the zeolite membrane costs a huge power in permeate compressor, compensating the power consumption reduction achieved with the membrane reactor. Thus, for coal-fired IGCC for electricity generation with 90% CO2 captured, the integration of the membrane reactor could provide a CO conversion ~99% and a significant drop in cost-of-electricity using zeolite membrane with H2 permeance >600 GPU and the H2/CO2 selectivity over 70.
- Research Organization:
- Arizona State Univ., Tempe, AZ (United States); Univ. of Cincinnati, OH (United States); Media & Process Technology, Pittsburgh, PA (United States); Nexant Inc., San Francisco, CA (United States)
- Sponsoring Organization:
- USDOE Office of Fossil Energy (FE)
- DOE Contract Number:
- FE0026435
- OSTI ID:
- 1618128
- Report Number(s):
- DOE-ASU-FE1111-1
- Country of Publication:
- United States
- Language:
- English
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