Novel synthesis of combined CaO-Ca12Al14O33-Ni sorbent-catalyst material for sorption enhanced steam reforming processes

Abstract

A properly CaO-Ca12Al14O33-Ni material with combined sorbent properties and catalyst activity was developed for H2 production from hydrocarbons via sorption enhanced steam reforming (SE-SR) with simultaneous CO2 capture. The combined sorbent-catalyst material (CSCM) was successfully prepared by multi-step approach method. At first a mixed calcium-aluminium oxide (CAO) ceramic was prepared by wet mixing/sintering method and used both as spacer for CaO-based sorbent and support for nickel catalyst. Subsequently, the sorbent and catalyst were prepared by wet mixing/sintering (900 °C) and wet impregnation/calcination (500 °C) methods, respectively. Then, an intimately powdery 1:1 mixture of two functional materials were cold-pressed and air-sintered at 900 °C obtaining the desired one-body sorbent-catalyst. The CSCM characteristics were investigated in detail by XRD, SEM-EDS, TG-DTG, BET physisorption, and TPR techniques. The CO2 sorbent properties were assessed over 200th multiple sorption/desorption cycles and the stabilizing role of spacer Ca12Al14O33 ceramic against sorbent decay was confirmed, whereas the presence of foreign Ni ions did not affect the sorbent CO2 carrying capacity. A H2-rich gas (> 90%) with low concentrations of CO2 and CO was produced over ten consecutive steam methane reforming (600 °C)/regeneration (750 °C) cycles at steam/carbon=3 molar ratio using CSCM. This good performance of SE-SR of methane process was attributed to the synergistic effect of high CO2 capture capacity and catalytic activity, the latter thanks also to the facile surface NiAl2O4 spinel to Ni° reduction in the low temperature range of 400–600 °C.