Integrated analysis of a membrane-based process for hydrogen production from ethanol steam reforming

The aim of this work is to investigate the performance and energy efficiency achieved by an integrated system based on two different ethanol fuel processor configurations: a Conventional Reactor (CR) and a Membrane Reactor (MR). The CR-based configuration system consists of an ethanol reformer followed by two water-gas shift reactors operating at high and low temperatures. The final hydrogen purification is carried out by a preferential oxidizer in order to reduce the CO concentration before feeding the polymer electrolyte membrane fuel cell (PEMFC). A multi-tubular MR process using thin Pd–Ag tubes has also been considered, where the water-gas shift reaction and the hydrogen separation take place simultaneously. The analysis showed that the MR process configuration possesses a simpler system design with a minor advantage in terms of energy efficiency (30%) compared with the conventional system (27%). Moreover, a detailed parametric analysis concerning the effects of water-to-ethanol molar ratio, reaction pressure, reformer and MR temperature, sweep-gas molar ratio and MR configuration on the achieved performance (hydrogen yield) and energy efficiency of the system has also been done. The importance of optimizing integrated systems is shown since the optimal operating conditions from a global efficiency analysis point of view are in general distinct when compared with those obtained when focusing on the reformer reactor or individual process units alone.