Experimental testing and model validation of the calcination of calcium carbonate by the reduction of copper oxide with CH4

Abstract

The reduction reaction of copper oxide with CH4 is highly exothermic and can be arranged to generate sufficient heat to in-situ calcine calcium carbonate and produce a highly concentrated stream of CO2. This concept is tested at TRL4 in a packed-bed reactor operated close to adiabatic conditions. The impact of the initial solids temperature and the inlet flowrate of the gases is evaluated. A 50/50 (vol.%) mixture of methane and hydrogen (i.e., a possible composition of the PSA-off gas generated in a reforming process) has also been used as reducing gas. The presence of H2 reduces the CuO/CaCO3 proportion required in the bed and promotes the calcination at temperatures lower than 870 °C. The experimental measurements are well predicted by a one-dimensional fixed-bed reactor model, in which the steam methane reforming, water–gas-shift, carbon deposition and carbon gasification reactions are also considered. Different characterization techniques (i.e., SEM, XRD, N2 adsorption, TPR) demonstrate that both commercial CuO- and CaO-based materials show good stability after successive cyclic experiments.