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

摘要

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 degrees C) and wet impregnation/calcination (500 degrees C) methods, respectively. Then, an intimately powdery 1:1 mixture of two functional materials were cold-pressed and air sintered at 900 degrees 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 H-2-rich gas (> 90%) with low concentrations of CO2 and CO was produced over ten consecutive steam methane reforming (600 degrees C)/regeneration (750 degrees C) cycles at steam/carbon = 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 degrees C.