Hydrogen production drawback

A major drawback in obtaining sustainable hydrogen production is the instability of the enzyme during continued operation. One approach is to use living cells, which have the ability to repair, maintain and reproduce themselves. The alternative would be to create a stable and inexpensive synthetic catalyst, which would mimic the properties of the natural enzyme, which is the rapid and reversible activation of H2 at water temperature (below 100°C) and near-neutral pH. Such a catalyst would be most welcome in... 

Three different routes, or combinations of these, can be used to produce synthesis gas from methane. These are steam reforming, CO2 reforming and partial oxidation. Each has its advantages and likewise has drawbacks. Steam reforming, which is a common industrial method of synthesis gas production, is very endothermic, as seen in the equations below. It also produces an H2/CO ratio of about 3/1, which is good for hydrogen production, but is too high for fuel synthesis. Methanol and Fischer-Tropsch synthesis use a H2/CO ratio of about 2/1. 

Reduction and oxidation step in two separate reactors allow for a continuous hydrogen production. A major drawback is the small conversion rate of 60 % of the synthesis gas in the reduction step. The effluent from the steam-iron reactor contains 37 % H2 plus 61 % steam and 96 % H2, respectively, if the steam is condensed. The remaining heating value plus sensible heat at 825 °C, however, can be used to cogenerate electricity. With a plant capacity of 110,000 Nm /h of H2, the byproduct electric power is 158 MW [55]. 

As a main scope, the present chapter will give an overview on the general classification of the membranes, paying particular attention to the palladium-based membranes and their applications, pointing out the most important benefits and the drawbacks due to their use. Finally, the application of palladium-based membranes in the area of the membrane reactors will be illustrated and such reaction processes in the issue of hydrogen production will be discussed. 

Because the number of carbons in the hydrocarbon is larger, an irreversible reaction easily can achieve higher conversions at moderate temperatures. The drawback of this conversion is that often two other reactions occur simultaneously, namely the water gas shift (WGS), which is beneficial for hydrogen production, and methanation, which in turn consumes the produced hydrogen to produce unwanted methane (Damle, 2009). 

It could be useful to give an overview of the studies present in the open Uterature on this reaction. Currently, only a few studies are focused on glycerol SR for hydrogen production. In particular, this reaction can be carried out in either aqueous or gas phase. When the reaction is performed in aqueous phase, its low catalyst deactivation is an advantage nevertheless, high pressures are required. On the other hand, in gas phase, the reaction can be carried out at atmospheric pressure, and, as a drawback, the catalyst is subject to a great deactivation (Htrai et al, 2005). 

Synthesis Ga.s, Since petroleum prices rose abmpdy in 1974, the production of ethanol from synthesis gas, a mixture of carbon monoxide and hydrogen, has received considerable attention. The use of synthesis gas as a base raw material has the same drawback as fermentation technology low yields limited by stoichiometry. 

---