Solar Thermal Reforming

Abstract

Virtually all hydrogen produced today is sourced from fossil fuels, with the principal method employed being the catalytic reforming of methane (CH4 , the principal component of natural gas and other gaseous fuels) [1]. Two different reactions can be distinguished in the methane reforming process: steam methane reforming (SMR) and C02 (or dry) methane reforming (DMR), represented by Eqs. (8.1) and (8.2) respectively: CH4 + H20 ~ 3 H2 +COD.H~98 K = +206 kJ 11101-I(8.1) CH,1 + C02 ~ 2 H2 + 2 CO; D.H~98 K = +247 kJ mol- 1; (8.2) Both reactions are highly endothermic, and are, thus, favored by high temperatures; industrial reforming processes are carried out between · 800 and 1000 °C [1 ]. The required energy is supplied by combustion of additional natural gas and process waste gas from the downstream hydrogen purification step. The share of natural gas consumed as fuel varies from 3% to 20% of the total plant's natural gas consumption [2]. The reaction gas product mixture is known as Synthesis gas (syngas): a gas mixture that contains varying amounts of CO and H2 whose exothermic conversion into fuel and other products has long been commercially practiced, for example, via the Fischer-Tropsch technology [3]. In fact hydrogen and syngas are the basic raw materials to produce synthetic liquid fuels (SLFs) and chemicals via industrially available processes.