Feedstocks oxygen sensitivity

Feedstocks come mainly from catalytic cracking. The catalyst system is sensitive to contaminants such as dienes and acetylenes or polar compounds such as water, oxygenates, basic nitrogen, organic sulfur, and chlorinated compounds, which usually require upstream treatment. 

Fortunately, the continued developments of the hydrodesulfurization process over the last two decades has resulted in the production of catalysts that can tolerate substantial amounts of nitrogen compounds, oxygen compounds, and metals without serious losses in catalyst activity or in catalyst life (Chapter 5). Thus, it is possible to use the hydrodesulfurization process not only as a means of producing low-sulfur liquid products but also as a means of producing low-sulfur, low-nitrogen, low-oxygen, and low-metals streams that can be employed as feedstocks for processes where catalyst sensitivity is one of the process features. 

The process is designed to utilize olefinic feedstocks from steam crackers, refinery FCC and coker units, and MTO units, with typical C4 to C8 olefin and paraffin compositions. The catalyst exhibits little sensitivity to common impurities such as dienes, oxygenates, sulfur compounds and nitrogen compounds. 

Brassylic acid, a 13-caihon saturated dibasic acid, can be derived from the oxidative cleavage of erucic acid and used as a feedstock for the production of nylon (Scheme 1). Brassylic acid is made by ozonolytic cleavage of erucic acid in acetic acid followed by oxidation of the resultant aldehyde by oxygen at elevated temperatures (100°C) to give the diacid. Crystallization from toluene gives a polymer-grade brassylic acid (6). Pilot-scale production of nylon-1313 (7) as well as nylon-613 was found to have exceptionally low sensitivity to moisture, excellent dimensional stability. and dielectric properties. Long-chain nylons of this type have found niche markets in automotive parts. 

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