Calcium-promoted catalytic activity of potassium carbonate for gasification of coal char: The synergistic effect unrelated to mineral matter in coal

摘要

The purpose of this work is to investigate the synergistic catalysis between calcium species and K_2CO_3 for the char gasification. Graphite and four mineral-free chars including an anthracite coal char, a bituminous coal char, a lignite coal char and a pine wood char were gasified at 750 ℃ in a stream of steam/argon under atmospheric pressure. It was found that each of three calcium species (Ca(OH)_2, Ca(CH_3COO)_2 or Ca(Ac)_2, and CaCO_3) synergistically promoted the catalytic activity of K_2CO_3 for the gasification of all samples, and the extent of promotion was dependent on calcium species and carbon or char samples. The formation of a eutectic from the calcium species/K_2CO_3 catalyst was proved to be an important mechanism for its better catalytic effect. The presence of the organically bound calcium on the char was also likely to be responsible for the promoted catalytic gasification.