Title

Hydrogen Production Via Photocatalytic Oxidation Of Aqueous Ammonium Sulfite Solutions

Keywords

Hydrogen production; Photocatalysis; Solar; Sulfur ammonia; Thermochemical cycles

Abstract

A new hybrid photo-thermochemical sulfur-ammonia (S-NH3) cycle is proposed. The cycle is a modification of the well-known Westinghouse hybrid cycle wherein the electrochemical step is replaced by a photocatalytic step. The new cycle utilizes both IR and visible light portions of the solar spectrum to achieve higher overall solar-to-hydrogen energy conversion efficiencies than those utilizing heat only. The main process, unique to the S-NH3 cycle, is the visible light-induced photocatalytic oxidation of ammonium sulfite (NH4)2SO3) with production of hydrogen and ammonium sulfate ((NH4)2SO4). The (NH 4)2SO4 product is processed to generate oxygen and recover NH3 and SO2, which are then recycled and combined with water to regenerate (NH4)2SO3 forming a closed cycle. In this paper, we report our experimental findings with regard to the photocatalytic oxidation of aqueous (NH4) 2SO3 solutions containing suspended platinum-doped cadmium sulfide (Pt/CdS) particles irradiated by a xenon arc lamp. We achieved energy conversion efficiencies (absorbed light to chemical energy of hydrogen) of about 12%. The photocatalyst remained active for more than 70 hrs. The experimental results for the photocatalytic step of the S-NH3 cycle describing the hydrogen generation kinetics and effects of temperatures, pH, catalyst preparation and platinum loading on the H2 production efficiencies are also discussed.

Publication Date

12-1-2006

Publication Title

16th World Hydrogen Energy Conference 2006, WHEC 2006

Volume

1

Number of Pages

591-599

Document Type

Article; Proceedings Paper

Personal Identifier

scopus

Socpus ID

84875585900 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/84875585900

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