Process for Elimination of Hexavalent Chromium Compounds on Metallic Substrates within Zero-PGM Catalyst Systems

Abstract

Process for manufacturing ZPGM catalysts systems that may allow the prevention of formation or the conversion of corrosion causing compounds, such as hexavalent chromium compounds, within ZPGM catalyst systems is disclosed. In one embodiment, disclosed ZPGM catalysts systems, may include metallic substrate, which may include alloys of iron and chromium, a washcoat and an overcoat. Disclosed manufacturing process may include a thermal decomposition of hexavalent chromium compounds which may allow the decomposition of such compounds into trivalent chromium compounds, and may also produce metallic catalyst, such as silver. Such conversion may prevent corrosion formation, such as red color corrosion within ZPGM catalyst system. An embodiment of the disclosed process may include a reducing agent, which may be present in exhaust conditions, which may convert hexavalent chromium compounds into trivalent chromium compounds as well as produce metallic catalyst, such as silver. Employing the disclosed manufacturing process may allow the production of ZPGM catalyst systems that may exhibit high activity and enhanced performance.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation of U.S. patent application Ser. No. 13 / 940,990, filed July 11, 2013, of which is incorporated herein by reference as if set forth in its entirety.BACKGROUND[0002]1. Technical Field[0003]The present disclosure relates generally to ZPGM catalyst systems, and, more particularly, to elimination of corrosion causing compounds on ZPGM catalyst systems.[0004]2. Background Information[0005]Ceramic substrates may dominate the car market, primarily because they are mass-produced and therefore less costly. However, metallic substrates may offer the industry of catalyst systems significant advantages.[0006]The substrate of a catalytic system may fulfill an important role in supporting the catalytic material and may be capable of withstanding some extremely arduous conditions. Operating temperatures may be in excess of 1000° C. and the substrate may also be exposed to fast moving, corrosive exhaust gases, rapid chang...

AI Technical Summary

Benefits of technology

The present patent discloses a process that can prevent the formation of hexavalent chromium compounds which can cause corrosion in zero platinum group metal (ZPGM) catalyst systems. The process involves thermal decomposition of hexavalent chromium compounds, which produces trivalent chromium compounds and metallic catalyst. This prevents corrosion formation and allows the production of ZPGM catalyst systems with high activity and performance.

Problems solved by technology

A major problem with manufacturing of catalyst systems may be the presence of corrosion in the catalyst systems.

Chromic acid vapor is a toxic compound, and thus undesirable.

Images