Hydrogen-generating reactions

Palladium and selective alloys with other metals can be fabricated into dense membrane reactors in foil or tubular form, mostly in thin layers to reduce permeation resistance. In 

Gas/vapor phase hydrogen-generating reactions using dense membrane reactors 

Water gas shift Fe304-Cr203 Pd on porous C =99%+ Uemiya et al.. 

Cr203-Al203 Dense Si02 on porous glass 

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Ce " can be used with light of shorter wavelength to promote the hydrogen generation reaction ... 

Hydrogenolysis and hydrogenation may occur in the absence of a catalyst but for rapid stabilization of, or effective addition of hydrogen to, the primarily formed lignin fragments, the application of a suitable catalyst is necessary The only exception to this principle are hydrogen-generating reactions which occur when primary alcohols and alkali are heated to temperatures in the vicinity of 350 °C... 

Similar to the case of dehydrogenation or other hydrogen-generating reactions, the use of a dense membrane reactor to remove oxygen from an oxygen-generating reaction such as decomposition of carbon dioxide displaces the reaction equilibrium and increases the conversion from 1.2% (limited by the equilibrium) to 22% [Nigara and Cales, 1986]. This has been confumed by Itoh et al. [1993]. 

Gas/vapor phase hydrogen>generating reactions using porous membrane reactors... 

Membranes with non-traditional surfaces have been suggested [Gryaznov et al., 1975]. Pd-based membranes in the form of cellular foils were fabricated and used to carry out a hydrogen-consuming and a hydrogen-generating reaction on the opposite sides of the membrane. The foils have oppositely directed, alternate projections of hemispherical or half-ellipsoidal shapes. This type of configuration, in principle, provides uniform... 

For the Level 2 analysis, we used the equilibrium module of HSC to obtain equilibrium data [HSC]. Figure 2 shows the equilibrium compositions for reaction 1, the hydrogen generation reaction, versus temperature. 

Apart from the ANL s current effort on Hybrid Cu-Cl Cycle, there have been only a limited number of other processes proposed for moderate temperature thermochemical hydrogen production. Dokiya and Kotera [3] proposed a cycle with a significant variant of the Hybrid Cu-Cl Cycle involving a direct electrochemical hydrogen generation reaction. More recently, Simpson et al. [4] have proposed a hybrid thermochemical electrolytic process for hydrogen production based on modified Reverse Deacon Reaction (generation of HCl gas) and gas phase electrolysis of HCl. 

Cu-Cl Cycle with Direct Electrochemical Hydrogen Generation Reaction... 

The Cu-Cl thermochemical cycle was first proposed by Carty et al. and was designated H-6 in a Gas Research Institute (GRI) report 151. In that study, H-6 consisted of four reactions, three thermal and one electrochemical. ANL s preliminary study indicated that two additional reactions should be added to the original H-6 cycle. So the proposed ALTC-1 cycle consists of six reactions. Reaction-1 is the hydrogen generation reaction and Reaction-6 is oxygen generation reaction [5]. The other reactions close the cycle. 

The hydrolysis of NaBH is an exothermic reaction and hydrogen generation reaction defined by the following formula ... 

If the above hydrolysis reaction occurs without the presence of catalysts, the hydrogen generation rate is quite slow (-0.6 mL min when 1.2 mmol sodium borohydride is dissolved in 10 ml distilled water [5]). To speed up the hydrogen generation reactions various catalysts can be used such as noble metals (Ru, Pt, Rh, Pd, Pt-Ru, Pt-Pd alloys) and non noble transition metals or related compounds (Cu, Co, Ni, Co-B, Co-P-B, Co-W-B, Ni-SiO, Fe-Ni alloys) [3]. 

The hydrogen generation reaction mechanism can be suggested as below when one of the most used precious catalysts, platinum, has been used in an aqueous solution of NaBH [37]. In this reaction mechanism, NaBH is adsorbed by the Pt catalyst. Later, this structure (NaBH. Pt) reacts with 2 moles of water. After the reaction, 4 moles of hydrogen gas and a by-product (NaBO ) on the catalyst are produced. 

The hydrogen generating reaction in negative electrode 2H20+2e -------------- H2T+20H-... 

Direct solution of the zinc electrode in the alkaline solution on open circuit is minimized by dissolving zinc oxide in the electrolyte and amalgamating the zinc in the electrode. Mercury levels used in zinc electrodes are usually in the range of 5 to 15% w/w. Great attention is also paid to the impurity levels in the zinc since minor cathodic inclusions in the electrode can drive the hydrogen generation reaction despite the precautions indicated. ... 

Different Biological Hydrogen Generation Reactions and Associated Microorganisms... 

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