Prevention of noble metal migration in bound zeolites during thermal oxidation
US5185306A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 24, 1991 |
| Grant date | Feb 9, 1993 |
| Priority date | — |
| Expiry date | Jul 24, 2011 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB01J29/068
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
Metal migration from molecular sieve particles to binder particles in agglomerates of molecular sieves bearing group VIII zerovalent metal occurs readily at temperatures above 350.degree. C. Such migration can seriously impair the performance of the catalyst whose effectiveness depends on the presence of the metal largely, if not exclusively, on the molecular sieve particle. Exposure of the catalyst, or a catalyst precursor, to temperatures facilitating group VIII metal migration can occur at various periods during the catalyst's history. Group VIII metal migration can be inhibited and often effectively prevented when chlorine or a chlorine-containing compound is present in the non-reducing atmosphere at temperatures which otherwise would bring about metal migration.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.