H.p.l.c. Quantitation of hydrocarbon class types in cracked products

H.p.l.c. was optimized to obtain quantitative compositional data on hydrocarbon class type (saturates, olefins, aromatics plus polars) in cracked products from vacuum gas oil (370-500°C) feed over REY zeolite catalyst in a micro-activity test unit. H.p.l.c. separation was achieved using an amino column, a backflush device and nC₆ as mobile phase. An RI detector was used to obtain total saturates and aromatics and a 200 nm u.v. detector to estimate olefins and aromatic hydrocarbons by ring number. Quantitation was achieved using external standard procedure and standards were prepared from the identical petroleum products to obtain response factors. A considerable variation in the liquid product yield during cracking reactions was noticed, from 40 to 70 wt%. Cracking reactions were also favoured through hydrogen transfer, increasing substantially the aromatic content in the range 50-70 wt%. Olefins were also formed during cracking, ranging from 5 to 10 wt%.