Reformate hydrocarbon

Phosphoric Acid Fuel Cell. Concentrated phosphoric acid is used for the electrolyte ia PAFC, which operates at 150 to 220°C. At lower temperatures, phosphoric acid is a poor ionic conductor (see Phosphoric acid and the phosphates), and CO poisoning of the Pt electrocatalyst ia the anode becomes more severe when steam-reformed hydrocarbons (qv) are used as the hydrogen-rich fuel. The relative stabiUty of concentrated phosphoric acid is high compared to other common inorganic acids consequentiy, the PAFC is capable of operating at elevated temperatures. In addition, the use of concentrated (- 100%) acid minimizes the water-vapor pressure so water management ia the cell is not difficult. The porous matrix used to retain the acid is usually sihcon carbide SiC, and the electrocatalyst ia both the anode and cathode is mainly Pt. 

Low energy pulsed (LEP) discharge is a simple hydrogen production process. This novel technique requires neither high temperature nor pressure die reaction takes place at room temperature and atmospheric pressure. We have successftilly reformed hydrocarbons using this LEP dischai e [1-6]. 

The fuel processor efficiency is size dependent therefore, small fuel cell power plants using externally reformed hydrocarbon fuels would have a lower overall system efficiency. 

In alkaline fuel cells (AFCs), the electrolyte is 34-46% KOH, immobilized on a porous support, and the operating temperature is 60-120 °C. Because the environment is alkaline, Raney nickel (a finely divided form of nickel) can be used in place of expensive platinum. However, the alkali will be neutralized by any CO2 in the hydrogen fuel, so AFCs are not suitable for operation with reformed hydrocarbons but can be fueled with alcohols or hydrazine. AFCs were used successfully on the Apollo space missions. 

Traditionally PSA processes have found particularly widespread application in hydrogen production systems wherein the PSA unit is used to produce ultra-high purity hydrogen (99.999%+) from steam-reformed hydrocarbons and other hydrogen sources. However, several limitations have existed with these processes. 

Carbon dioxide is made by steam-reforming hydrocarbons (Fig. 1), and much of the time natural gas is the feedstock. 

FIGURE 1 Hydrogen production by steam reforming hydrocarbon feedstocks. 

Recently, there has been significant interest in developing technologies for converting fossil fuels to hydrogen in small-scale systems. This paper presents a novel method of steam reforming hydrocarbon fuels to produce hydrogen. 

Tindall, B.M. and Crews, M.A., 1995, Alternative technologies to steam-methane reforming, Hydrocarbon Processing, ll,p75. 

Reforming hydrocarbons other than methane, notably oil products, can be achieved with reactions similar to (2.1) ... 

Suetsuna, T., Suenaga, S., and Fukasawa, T. Monolithic Cu-Ni-based catalyst for reforming hydrocarbon fuel sources. Applied Catalysis. A, General, 2004, 276 (1-2), 275. 

Christensen, T.S. Primdahl, I.I. Improve syngas production using autothermal reforming. Hydrocarbon Process 1994, March. 

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