(142a) Adsorption and Membrane Processes in Hydrogen Production

Ritter, J. A., University of South Carolina
Ebner, A. D., University of South Carolina

A Chemical Industry Vision 2020 sub-committee was established in June 2004 and chartered with the responsibility of identifying research and development needs for separation technology to drive equilibrium processes for the Chemical and Petrochemical Industry. This study focused on the anticipated drivers and requirements of the chemical and petrochemical industries. Chemical production processes were selected for review. This report, the first in a series, is directed to commercial, industrial hydrogen production. The growing requirements for hydrogen in chemical manufacturing, petroleum refining and the new emerging clean energy concepts will place greater demands on sourcing, production capacity and supplies.

A review was conducted of the current state of the art and emerging literature concepts on both adsorption and membrane separation technology applicable to H2 production. Recommendations for future R&D needs are discussed. An emphasis is placed on flow sheet design modification with adsorption or membrane units being added to existing plants for near term impact, and on new designs with complete flow sheet modification for new adsorption or membrane reactor/separators replacing current reactor and separator units in an existing plant for a longer term sustainable impact.

About 41 MM tons/yr of H2 is produced worldwide, with 80% of it being produced from natural gas by steam reforming, partial oxidation or autothermal reforming. H2 is used commercially to produce CO, syngas, ammonia, methanol and higher alcohols, urea and hydrochloric acid. It is also used in Fischer Tropsch reactions, as a reducing agent (metallurgy), and to upgrade petroleum products and oils (hydrogenation). Current industrial practices are summarized in terms of the key reforming and shift reactions and reactor conditions, with the four most widely used separations techniques --absorption, adsorption, membrane and cryogenic. As all of these reactions are reversible, the H2 or CO or syngas production from natural gas and hydrocarbon feedstocks is equilibrium limited and consequently provides opportunities for process improvement

It has been estimated that the reforming of natural gas to produce H2 consumes about 31,800 Btu/lb of H2 produced. It is further estimated that 450 trillion Btu/yr could be saved with a 20% improvement in just the H2 separation and purification train after the H2 reformer. This energy savings is a major driver for future R&D and for implementation of adsorption or membrane separation technology.

Recommendations for future separations R&D are set forth in ? Adsorbent Materials Development, Membrane development, Plant Design modification with additional separations systems, and Plant systems optomization. Detailed performance requirements are provided in the report. An overview of this report will be given during this presentation.