Xylene Isomerization Process and Catalyst Therefor
a technology of isomerization process and catalyst, which is applied in the direction of hydrocarbon preparation catalyst, physical/chemical process catalyst, bulk chemical production, etc., can solve the problems of complex process arrangement and high cost, and achieve the effect of convenient determination by electron microscopy
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example 1
[0054]Three ZSM-5 crystals listed below in Table 1 were prepared to investigate the effects of silica / alumina ratio and crystal size in a process according to the present invention.
TABLE 1Crystal Sizes,ZSM-5 CrystalsSiO2 / Al2O3 RatiosmicronI250.5II60III25
[0055]The crystals were ion exchanged to proton form and extruded into 1 / 20″ (about 0.127 cm) extrudates with an alumina binder. The weight ratio of crystal to binder was 4. The extrudates were calcined at 538° C. The extrudates were evaluated using a feed of 13.28 wt % para-xylene, 63.72 wt % meta-xylene, 17.94 wt % ortho-xylene, 1.52 wt % ethylbenzene, 1.28 wt % toluene, and 2.25 wt % non-aromatics, and low levels of benzene and nine-carbon aromatic compounds. The tests were performed in a ¼″ (about 0.635 cm) stainless steel reactor with the feed going up flow through the catalyst bed. Test conditions are listed below in Table 2.
TABLE 2Flowrate, WeightCatalystReactorReactorHourly SpaceCrystalsloading, gtemp., ° C.pressure, psigVelo...
example 2
[0057]Two parallel runs were conducted to investigate the effect of feed contaminants phenol and styrene on liquid phase isomerization. Catalyst was 1 / 20″ (about 0.127 cm) catalyst extrudates prepared from Catalyst III. Run #1 used Test Feeds and Run #2 used Reference Feeds (free of styrene and phenol). Typical compositions of the two feeds are 3.6-4.7 wt % paraxylene, 57.9-60.4 wt % metaxylene, 24.8-26.0 wt % orthoxylene, 8.7-9.5 wt % ethylbenzene, 0.15-0.19 wt % toluene, 1.2-2.8 wt % non-aromatics, and low levels of benzene and nine-carbon aromatic compounds. Test Feeds contained 20 ppm styrene and 2 ppm phenol.
[0058]Performance tests were conducted in a ¼″ (0.635 cm) stainless steel reactor with the feed going up flow through a catalyst bed. Test conditions are listed below in Table 3.
TABLE 3ReactorFlowrate, WeightCatalystReactorpressure,Hourly Spaceloading, gtemp., ° C.psigVelocityRun #1 with0.5056235, 2552651.5-2.6Test FeedRun #2 with0.5150235, 2552651.8-2.5Reference Feed
[0059]...
example 3
[0060]The following experiments were run using the preferred catalyst of the invention on various feedstreams (Table 4) at the same conditions, including a temperature of 255° C. and 2.1 hr−1 (WHSV). Experiments were run in a micro-unit; “PX concentration decrease (%)” is paraxylene decrease relative to other C8 aromatic hydrocarbons in the product versus feed, and are extrapolations based on observed trends for six months (run 1 and 2), one week (run 3), and 2 weeks (2 weeks).
TABLE 4RunPhenol, ppmStyrene, ppmPX concentration decrease (%)1000 (i.e. no deactivation)2220032434.344204.7
[0061]Two styrene concentrations studied were 20 and 43.2 wppm. The temperature of testing was 255° C. for both feeds. Catalyst aging data showed that with 43.2 wpm styrene in the feed, the LPI catalyst deactivated at a rate of 4.3% decrease in PX yield per year (Table 1).
[0062]Two phenol concentrations studied were 2 and 4 wppm. Temperatures of testing were 255 and 275° C. for the 2 wppm phenol feed, an...
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