Hydrogen production from hydrocarbons, minimizing

The photolysis of n-butane follows a pattern similar to that of propane, with many corresponding reactions. As found for previous hydrocarbons the photolysis includes both molecular and free-radical processes. The molecular elimination of Hj and Dj from C4H10-C4D10 mixtures was first shown by Sauer and Dorfman, who concluded that at 1470 A more than 90 % of the hydrogen came from molecular processes. On the basis of a study of the decomposition of excited -butane molecules generated by electron impact , they attributed hydrogen, methane, ethylene, and other hydrocarbon products to molecular processes, and concluded that free-radical reactions were minimal. 

HyChlor Formerly called DHC. A catalytic hydrodechlorination process which converts organic chlorides to hydrogen chloride and saturated hydrocarbons. The UOP HyChlor process recovers and recycles both the organic and inorganic reaction products in order to minimize waste disposal requirements and maximize yield. Used for treating wastes from the production of chlorinated petrochemicals such as vinyl chloride. Developed by UOP but not commercialized as of 1992. 

If one cannot diffuse the asphaltenes to the catalyst, why not diffuse the catalyst to the asphaltenes Dispersed catalysts also can be continuously added in sufficiently low enough amounts (i.e., 100 ppm) to consider them throwaway catalysts with the carbonaceous by-product. However, economics usually dictate some form of catalyst recycle to minimize catalyst cost. Nevertheless, by designing the reactor to maximize the solubility of the converted asphaltenes, the conversion of vacuum resids to gas and volatile liquids can be above 95% with greater than 85% volatile liquids. However, the last 5-10% conversion may not be worth the cost of hydrogen and reactor volume to produce hydrocarbon gases and very aromatic liquids from this incremental conversion. The answer depends on the value and use of the unconverted carbonaceous liquid by-product. 

The results in table 10 refer to initial catalytic activity 10 mins after addition of the hydrocarbon to the stream. The trend in all cases is for hydrogenation activity to subside with time. The final column contains data from an optimally conditioned catalyst for comparison. It is concluded that in order to minimize pentane production and maximize branched product the catalyst should be exposed to H2/H20 prior to admission of 1-pentene. 

Hydrocarbons can have many different effects on FC performance depending on their structure. Methane acts as an inert species in the fuel diluting the concentration, but does not interact strongly with the catalyst surface to disrupt the HOR. Aromatic hydrocarbons interact more strongly with the catalyst surface and tend to hydrogenate to cycloparaffins (Bender et ah, 2009). While this is a parasitic consumption of Hj, the effect of 20 ppm toluene on FC performance was minimal. Oxygenated hydrocarbons such as formic acid (HCOOH) and formaldehyde (HCHO) were explored in the literature because they are intermediate products of methanol reforming. The behavior of PEMFCs when exposed to formic acid or formaldehyde in Hj is very similar to CO it is characterized by initially rapid decreases in PEMFC performance followed by a saturation period and partial recovery when the contaminant is removed from the Hj (Narusawa et ah, 2003). 

---