Published March 2007
This Review presents a condensed picture of the research and development (R&D) work pertaining to hydrogen and hydrogen production methodologies. The review is based upon the R&D findings published during the last fifteen years in various technical journals of the world. The subject issues have been discussed generally in the broader terms.
The study presents the production processes in segmented form. The elements of discussion are outlined as: a) feedstocks; b) reforming; c) reformers; d) water-gas shift reaction; e) hydrogen purification; and f) hydrogen storage.
Hydrogen is produced in large quantities both as a targeted product as well as a by-product. Globally, approximately 94.6% of the intentionally produced hydrogen finds a captive use in the manufacture of ammonia (58.5%), refinery hydroprocessing operations (25.9%), and methanol (9.8%). Merchant uses of hydrogen are nominal, standing at just 4.3%. Total production of on-purpose hydrogen is a little more than 18.7 trillion standard cubic feet per annum. The main commercial technology for hydrogen production is steam reforming of natural gas or refinery naphtha, although refinery off-gases and heavy residue are also an important source of hydrogen.
Tightening regulatory standards for fuel sulfur and use of heavier crude slates having higher contents of sulfur and lower contents of hydrogen in developed countries are greatly impacting hydrogen demand. The vision of having a super-clean fuel and an economy based upon hydrogen have turned hydrogen into an extensively researched subject. A tremendous amount of technical information is now available on hydrogen. A technical review of such a vastly studied topic would need several publications for a comprehensive treatment. In this Review, therefore, only the most salient points of production-related issues are dealt with.