Pyrolysis of naphtha-raffinate

Summary

• 1. Analysis of the hydrocarbon composition of a commercial sample of raffinate from catalytic reformer naphtha has shown that it consists of 88% paraffins, out of which about 52% consists of isoparaffins, including some 40% monosubstituted compounds.

• 2. The experiments at 850°C demonstrated that the optimal pyrolysis regime was obtained at this temperature with a corresponding contact time of 0.5 sec; gasification was 81.8%, ethylene yield 32.8%, and propylene yield 16.2% of feedstock weight.

• 3. After mathematical treatment of the experimental results, equations were derived for determining the ethylene and propylene yields as functions of temperature and contact time, these equations being applicable to this feed-stock with processing temperatures of 700–850°C and contact times of 0.3–1.1 sec.

• 4. On the basis of the yields of the desired olefinic hydrocarbons that were obtained in the high-temperature pyrolysis regime, this raffinate can be characterized favorably as a pyrolysis feedstock. The hydrocarbon composition of the raffinate is such that greater propylene yields can be obtained, and the ethylene and propylene regimes in effect coincide.