The Structure Effect on the Activity and Strength of an Industrial Honeycomb Catalyst Derived from Different Ti Sources

Yunjia Li,Shiqiu Gao,Lin Huangfu,Abdullahi Abubakar,Jianling Li,Jian Yu,Changming Li

doi:10.3390/catal10010042

Abstract

A new honeycomb production process was proposed with both filter cake (from hydrothermal treatment of metatitanic acid) and industrial titanium dioxide as Ti sources. The strength of the obtained pilot product was comparable with the current industrial honeycomb product from only filter cake, but its denitration (DeNOx) efficiency was elevated up to 15 percentage points. Multiple characterizations revealed the filter cake and industrial titanium dioxide to be composed of primary particles and secondary particles, respectively, and the introduced secondary particles from industrial titanium dioxide resulted in increased specific surface area and pore size/volume, facilitating the exposure of more active sites with improved activity. Moreover, a positive correlation property was found between the honeycomb strength and crystallinity for the samples from different titanium sources. The filter cake with rich hydroxyl groups and weak crystallinity could be fused more easily among these primary particles to have a higher strength than industrial titanium dioxide, and the primary particle of the filter cake could fill the pile pore of industrial titanium dioxide and act as a solid phase binder to acquire good strength for the honeycomb using both the filter cake and titanium dioxide as Ti sources. The improved honeycomb product with good activity and strength may have more widespread application for the purification of low temperature flue gas in industry.

Highlights

Selective catalytic reduction with NH3 (NH3 -SCR) is the most popular technology to eliminate the emission of nitrogen oxides (NOx ) from industrial flue gas, in which the DeNOx catalysts play the key role due to their high denitration (DeNOx ) efficiency [1–4]
An improved process for honeycomb production was proposed by using both the filter cake and industrial titanium dioxide as Ti sources, and the DeNOx activity of the obtained honeycomb could be elevated up to fifteen percent together with the comparable strength of the honeycomb produced by only the filter cake
The structure study for the powdery catalyst showed that the filter cake consisted of primary particles with few pores and a small specific surface are, but industrial titanium dioxide consisted of secondary particles with abundant pile holes

Summary

Introduction

Selective catalytic reduction with NH3 (NH3 -SCR) is the most popular technology to eliminate the emission of nitrogen oxides (NOx ) from industrial flue gas, in which the DeNOx catalysts play the key role due to their high denitration (DeNOx ) efficiency [1–4]. As the most common commercial catalyst, the honeycomb DeNOx catalysts are largely produced though an extrusion process using industrial titanium dioxide or titanium-tungsten as Ti sources [5–7]. The pilot test of the produced honeycomb confirmed the good DeNOx activity for the purification of low temperature flue gas from a coking plant [9], and the corresponding low temperature DeNOx technology has obtained good application in industry in the past two years [10]. Compared with honeycomb catalyst produced by industrial titanium dioxide, our honeycomb showed significantly increased axial strength (5.3 MPa) with a high volume density (650 kg/m3 ). The strength of the honeycomb is a very important technical index for a low temperature DeNOx catalyst to keep the catalyst intact in high humidity flue gas and during the regeneration process

Methods

Results

Conclusion