Effects on activity of superhigh-silica cracking catalysts from high-temperature treatment with air and steam

Abstract

The authors study the influence of conditions of high-temperature air and steam treatment in cracking a hydrocarbon feedstock and in regenerating the catalyst on the activity of SHS zeolites and catalysts based on these zeolites. A TsVM-361 SHS zeolite was used in the studies. The conditions of catalyst activation, the procedures used to monitor the degree of crystallinity and the method of determining the activity in the model reaction of nheptane cracking are described. The authors found that steam treatment of the SHS zeolites reinforces the hydrophobic properties of their surface, and this leads to a decrease in the n-heptane conversion on the SHS catalyst to be a factor of approximately 4. By varying the conditions of a special calcination in air and subsequent steaming with unsaturated steam, and also varying the paraffin feedstock mass velocity, a satisfactory level of stability of activity can be brought about.