Green synthesis of ZSM-5 zeolite for selective catalytic reduction of NO via template-free method from tailing residue

Abstract

The task of circular economy in mining industry is to develop and utilize a large number of tailing residue that has been shelved for a long time. An economical and sustainable utilization strategy of potassium feldspar tailing residue is reported. The ZSM-5 zeolite catalysts using tailing residue as raw materials by a template-free hydrothermal method are synthesized for selective catalytic reduction (SCR), abandoning the high pollution and energy consumption method of zeolite synthesis from fine chemicals. The effects of feed NaOH and Al2(SO4)3·18H2O on tailing residue and zeolite products are systematically studied, which proved that the silicon and aluminum elements in the tailing residue can be efficiently utilized. The results of scaling up experiment and experiment without additional aluminum confirm the feasibility and repeatability of tailing residue utilization. The synthesized ZSM-5 was used to prepare the Ce-Fe-ZSM-5 catalyst for NO reduction to N2 and showed excellent activity, with the NOx conversion remaining above 80% at the range of 300 °C~500 °C. The synergistic effect of Ce and Fe ions promoted the formation of more chemisorbed oxygen and accelerated the reaction rate of NO and NH3 adsorbed on the catalyst surface, resulting in a significant increase in the low-temperature activity of 1%Ce-Fe-ZSM-5. In this study, zeolite catalysts with excellent catalytic effect from tailing residue that can be used in petrochemical fields are successfully synthesized. The route is economic, environmental, and recyclable, which provides an opportunity for comprehensive development and application of tailing residue.