Ca12al14o33 or Mgo Supported Ni-Carbide Slag Bi-Functional Materials for H2 Production and Co2 Capture in Sorption-Enhanced Steam Gasification of Cellulose/Polyethylene Mixture

Abstract

Co-gasification of biomass and waste plastics is a promising technology for H2 production. In this work, Ni-CaO-Ca12Al14O33 (Ni-CaO-CAO) and Ni-CaO-MgO bi-functional materials were prepared from carbide slag for H2 production in sorption-enhanced steam gasification (SESG) experiments of cellulose/polyethylene mixtures. The H2 production and CO2 capture performances of Ni-CaO-CAO and Ni-CaO-MgO in SESG of cellulose/polyethylene were studied and compared. Density functional theory (DFT) calculations, including the density of states, electron differential densities, and adsorption energies were performed to investigate the effect of supports on stability and reactivity of Ni-CaO based bifunctional materials at a microscopic level. The results exhibit that polyethene contributes to improving the H2 production effectiveness of cellulose SESG, the optimum mass ratio of cellulose to polyethene is 0.5:0.5. The CO2 capture capacity, H2 yield, and H2 concentration using Ni-CaO-CAO can be respectively 2.0, 2.6, and 1.4 times as high as those using Ni-CaO-MgO in the 20th cycle, which indicates the higher cyclic stability and catalytic activity of Ni-CaO-CAO. DFT results also indicate the CAO can better retain the stable structure of Ni-CaO-based materials, which is consistent with the experimental results. Compared with MgO, Ca12Al14O33 is a better framework for Ni-CaO-based bifunctional material for H2 production in the SESG process.

Keywords: Sorption-enhanced steam gasification, Cellulose/polyethylene mixture, H2 production, CO2 Capture, Ni-CaO-Ca12Al14O33 bi-functional material, density functional theory