Ceramic Candle Filter with Pd/V/Ti Catalyst for NOx and Soot Removal
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Solution Overview
Problem
Conventional ceramic candle filters are effective in removing particulate matter but struggle with the simultaneous reduction of harmful gaseous pollutants like NOx, VOC, and CO due to limitations in catalyst selectivity and activity, particularly with vanadium oxide-based catalysts.
Innovation Solution
A ceramic candle filter with a combined SCR and oxidation catalyst comprising palladium, vanadium oxide, and titania is used, arranged on the dispersion side and/or within the filter walls, which enhances the oxidation of hydrocarbons and selective catalytic reduction of NOx, while being sulfur-resistant and reducing ammonia and carbon monoxide slips.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a vanadium oxide-based catalyst is used for NOx reduction, then selective catalytic reduction of NOx is achieved, but CO oxidation is insufficient and ammonia slip increases
Solution Approach 1:
The patent combines two catalyst functions into a single catalytic layer: vanadium oxide for SCR of NOx and palladium for CO and hydrocarbon oxidation. This merging resolves the contradiction by making the catalyst system simultaneously effective for both NOx reduction and CO oxidation, while the titania support enhances overall catalytic activity and reduces ammonia slip.
Solution Approach 2:
The catalyst is formulated as a composite material containing vanadium oxide, palladium, and titania. This composite structure allows each component to contribute its specific catalytic properties: vanadium oxide for NOx reduction, palladium for CO oxidation, and titania for enhancing overall performance and reducing harmful slips.
2Object-generated harmful factors
If a combined SCR and oxidation catalyst is used, then CO and hydrocarbon oxidation is improved, but catalyst complexity increases
Solution Approach 1:
The catalytic layer is designed as a multi-functional system where a single catalyst composition performs multiple functions: vanadium oxide for SCR, palladium for oxidation of CO and hydrocarbons, and titania for enhancing overall catalytic activity. This universality reduces the need for separate catalyst stages while achieving comprehensive pollutant control.
3Reliability
If conventional ceramic candle filters are used, then particulate matter removal is effective, but gaseous pollutant reduction is insufficient
Solution Approach 1:
The patent merges the particulate filtration function of the ceramic candle filter with the gaseous pollutant reduction function of the catalytic layer. The catalytic layer is applied directly on the filter surface, creating an integrated system that simultaneously captures particles and reduces gaseous pollutants like NOx, VOC, and CO in a single pass through the filter.
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 Pd/V/Ti catalyst achieves high efficiency in removing particulate matter and reducing nitrogen oxides and hydrocarbons, with reduced ammonia and carbon monoxide emissions, and is sulfur-resistant, offering improved pollutant control compared to traditional catalysts.
Implementation Method 1
reducing amounts of nitrogen oxides and hydrocarbons in the off- or exhaust gas by oxidation of the hydrocarbons and by selective catalytic reduction (SCR) of the nitrogen oxides with the nitrogenous reductant
Implementation Method 2
oxidation of the hydrocarbons and by selective catalytic reduction (SCR) of the nitrogen oxides
Implementation Method 3
passing the off-gas or the exhaust through a ceramic candle filter and capturing the particulate matter
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 arranged at least on the dispersion side and/or within wall of the filter, the combined SCR and oxidation catalyst comprises palladium, a vanadium oxide and titania.