Ceramic Candle Filter with Dual-Sided Catalyst for Exhaust Gas
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Solution Overview
Problem
Conventional ceramic candle filters struggle to effectively remove a wide range of pollutants, including NOx, VOC, CO, and ammonia, from process off-gases and engine exhaust gases, particularly due to limitations in catalyst selectivity and efficiency, especially when dealing with high temperatures and sulfur-containing gases.
Innovation Solution
A ceramic candle filter with a combined SCR and oxidation catalyst comprising vanadium oxide and titania on the dispersion side, combined with a palladium catalyst on the permeation side, which enhances the removal of particulate matter, hydrocarbons, and nitrogen oxides, while minimizing ammonia and carbon monoxide slip, and is resistant to sulfur deactivation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a vanadium oxide catalyst is used for NOx reduction by selective reduction with NH3, then NOx removal efficiency is improved, but ammonia slip increases and CO oxidation is insufficient
Solution Approach 1:
The patent combines vanadium oxide catalyst (for NOx reduction) with palladium catalyst (for CO oxidation and ammonia slip control) into a single integrated filter system. The vanadium oxide component provides selective catalytic reduction of NOx with NH3, while the palladium component simultaneously oxidizes CO and controls ammonia slip, achieving multiple pollution control functions in one device
Solution Approach 2:
The catalytic filter is designed to perform multiple functions simultaneously: NOx reduction via SCR reaction, CO oxidation, VOC oxidation, and ammonia slip control. This multi-functional catalyst system replaces the need for separate treatment devices, making the filter universal for handling multiple pollutants in flue gas
2Manufacturing precision
If conventional ceramic candle filters are used for particulate matter removal, then filtration efficiency is improved, but they cannot effectively remove gaseous pollutants like NOx, VOC, CO, and ammonia
Solution Approach 1:
The patent merges the particulate filtration function of ceramic candle filters with the gaseous pollutant removal function of catalytic materials. The ceramic filter structure provides physical filtration of particulates, while the integrated vanadium oxide and palladium catalysts on the filter surface simultaneously catalyze the conversion of gaseous pollutants (NOx, VOC, CO, ammonia), achieving combined particulate and gas phase pollution control in a single device
3Productivity
If high porosity (70-90%) is used in ceramic candle filters, then pressure drop is reduced and filtration activity is maintained, but mechanical strength and stability decrease
Solution Approach 1:
The patent employs composite material structure combining ceramic fibers (for mechanical strength and thermal stability) with catalytic materials (vanadium oxide and palladium on alumina support). The ceramic matrix provides the structural framework with adequate mechanical strength, while the catalytic components are deposited on the surface and within pores, maintaining high porosity for low pressure drop while adding the necessary catalytic functionality for gas phase pollution control
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution achieves high efficiency in removing particulate matter and gaseous pollutants, with minimal CO emission and sulfur resistance, allowing for effective treatment of process off-gases and engine exhaust gases with reduced catalyst loading and operational costs.
Implementation Method 1
oxidation catalyst consisting of palladium and vanadium oxide supported on a carrier
Implementation Method 2
catalyst material for selective catalytic reduction of NOx in the presence of ammonia
Implementation Method 3
CO cannot be oxidized to CO2 at a feasible reaction rate by contact with the vanadium oxide catalyst, but requires presence of a noble metal catalyst, e.g. Pd
Implementation Method 4
porous filter structure with a first and a second face where the pores of the porous structure form passages for flue gas between said first and second faces
Data Source
AI summary
Ceramic candle filter and use of the filter in the removal of particulate matter in form of soot, ash, metals and metal compounds, together with hydrocarbons and nitrogen oxides being present in process off-gas or engine exhaust gas, the filter comprises a combined SCR and oxidation catalyst being arranged on the dispersion side and within wall of the filter; and a palladium comprising catalyst arranged on the permeation side and within wall of the filter facing the permeation side.