Gasoline paraffin yield

The reduction in the yield of gasoline range paraffins (as a per cent of feed) due to 1% thermally treated ZSM-5 was about 40%. Paraffin yield reduction to a lesser extent was observed with the steam treated ZSM-5. Thus, enrichment of olefins and aromatics in the gasoline occurred with the addition of either thermally treated or steam treated ZSM-5. 

Table VI shows the detailed gasoline composition (as a per cent of fresh feed), particularly the breakdown of the straight chain and branched paraffins. The results show an increase in the ratio of the branched to straight chain paraffins for each carbon number when ZSM-5 is used. This is particularly striking in that the total paraffin yield is unchanged when ZSM-5 is added. Thus, although the total paraffin yield remains essentially unchanged, the iso/normal paraffin ratio increases for all carbon numbers. There is also a change in the paraffin carbon number distribution in that the Cq and Cg paraffin yields decrease and the C5 and Cg paraffin yield increases. The normal paraffins are decreasing at a faster rate than the isoparaffins despite the fact that their initial concentration is 5 to 10 times lower. In the C7 carbon number, catalyst A shows an increase in the isoparaffins while catalyst B shows a decrease. The normal C7 decreases for both catalysts.

In general, FCC feeds are predominately paraffinic. The paraffinic carbon content is typically between 50 wt% and 65 wt% of the total feed. Paraffinic stocks are easy to crack and normally yield the greatest amount of total liquid products. They make the most gasoline and the lea.st fuel gas, but also the lowest octane number. 

In the previous examples, the feed characterizing correlations in Chapter 2 are used to determine composition of the feedstock. The results show that the feedstock is predominantly paraffinic (i.e., 61.6% paraffins. 19.9% naphthenes, and 18.5% aromatics). Paraffinic feedstocks normally yield the most gasoline with the least octane. This confirms the relatively high FCC gasoline yield and low octane observed in the test run. This is the kind of information that should be included in the report. Of course, the effects of other factors, such as catalyst and operating parameters, will also affect the yield structure and will be discussed. 

Paraffinic feedstocks produce the most gasoline yield (but the lowest octane). The common indicators of any increase in feed par-affinicity are ... 

Oxyhydrochlorination A two-stage process for making gasoline from lower paraffinic hydrocarbons, especially methane. The methane, mixed with oxygen and hydrogen chloride, is passed over a supported copper chloride catalyst, yielding a mixture of chloromethanes ... 

The PONA results at constant conversion (72 vol%) in the series from EKZ4 to BETA 500 show gasoline olefin content increased from 8.6 percent to 16.4 percent, paraffin content decreased from 54.7 percent to 46.8 percent, and naphthene and aromatics contents remained constant. Research octane increased 4.2 numbers while motor octane increased 1.2 numbers. The aromatics content of the LCO as measured by the aniline point decreased with the aniline point increasing from 42 to 62. LCO yield increased from 16.0 volume percent to 18.0 volume percent, while the coke yield decreased dramatically from 4.2 percent to 2.4 percent. 

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