The opportunities and challenges for SCR-DeNOx facing coalbed methane power generation

Abstract

Coalbed methane (CBM) is an important resource in the world, and CBM power generation is supposed as the most effective method to make utilization of the low-concentration methane. In this context, efficient nitrogen oxides (NO_x) removal is of paramount importance, where the long-term stable operation of zeolite catalyst is significantly challenged under high temperature, high NO_x concentration, high humidity, and high gas hourly space velocity conditions (abbreviated as ‘four high’). Herein, in view of the characteristics of exhaust gas, potential reactions that occurred including ammonia-selective catalytic reduction (NH₃-SCR), hydrocarbon-selective catalytic reduction (HC-SCR), carbon monoxide-selective catalytic reduction (CO-SCR), the competitive oxidation reaction between CH₄ and CO are reviewed in detail, such as the catalysts, influencing factors and reaction mechanisms. Besides the excellent NO_x conversion, anti-aging, anti-poisoning, and anti-sintering performance are essential in this field. Furthermore, preparing the low-cost zeolite derived from solid waste represents an efficient and promising integration the disposal of coal fly ash and coal gangue, as well as the removal of NO_x. This review not only proposes the theoretical system and construction strategy of denitrification catalysts, but also contributes the theoretical basis for efficient NO_x removal of the CBM power generation, and collaborative control of gas pollution in accordance with ‘treating exhaust with gas’ and ‘treating exhaust with coal’ guidelines.