Application of surface-modified metal hydrides for hydrogen separation from gas mixtures containing carbon dioxide and monoxide

Application of surface-modified MH material for H 2 separation using temperature/pressure swing absorption–desorption was studied. The substrate alloy had the following composition LaNi 3.55 Co 0.75 Al 0.4 Mn 0.3 , and the surface modification was carried out through fluorination followed by aminosilane functionalization and electroless deposition of Pd. The material was found to have good poisoning tolerance towards surface adsorbates, even for the large (∼1.5 kg) batches. Feasibility of its application for H 2 separation from gas mixtures (up to 30% CO 2 and 100 ppm CO) was demonstrated by testing of a prototype H 2 separation system (∼280 g of MH in two reactors), and H 2 separation reactor (0.75 kg of MH). The H 2 separation was characterized by stable performances in the duration of 250 absorption/desorption cycles. However, the total process productivity was found to be limited by the sluggish H 2 absorption (partial H 2 pressure ⩽2.5 bar, temperature below 100 °C). In the presence of CO 2 and CO, additional deceleration of H 2 absorption was observed at space velocities of the feed gas below 5000 h −1 .