Steam cracking of hydrocarbons 3. Straight-run naphtha Citation for published version (APA): Bajus, M., Vesely, V., Leclercq, P. A., & Rijks, J. A. (1980). Steam cracking of hydrocarbons 3. Straight-run naphtha. Industrial and Engineering Chemistry. Product Research and Development, 19(4), 556-563. DOI: 10.1021%2Fi360076a015, 10.1021/i360076a015 DOI: 10.1021%2Fi360076a015 10.1021/i360076a015 Document status and date: Published: 01/01/1980 Document Version: Publisher’s PDF, also known as Version of Record (includes final page, issue and volume numbers) Please check the document version of this publication: • A submitted manuscript is the version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. 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If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license above, please follow below link for the End User Agreement: www.tue.nl/taverne Take down policy If you believe that this document breaches copyright please contact us at: [email protected] providing details and we will investigate your claim. Download date: 08. May. 2019 556 Id.Eng. Chem. Prod. Res. Dev. 1980, 19, 556-563 The results of the current study support the view that the two properties which have caused problems in other cop- principal role of COz is to maintain the catalyst in an active per-based methanol synthesis catalysts (Dewing and Davis, state rather than to take place in a direct hydrogenation 1975). to methanol. Literature Cited Conclusions Casev. T. D.: ChaDman, G. M. (to' Cataksts and Chemicals. Inc.), US. Patent 3 790 505, Fib 5. 1974. This study has demonstrated that novel catalysts of the Chang, C. D.; Sihrestrl. A. J. (to Mobile Oil Corporation), US. Patent 3 894 102, lune 1975. Raney type, produced by the caustic extraction of alu- I-'.- -. minum-copper-zinc alloys shows high activity and selec- Davles, P.; Snowdon, F. E. (to Imperial Chemical Industries Ltd.), US. Patent 3 326 956,June 20, 1967. tivity for methanol synthesis. The main factors which Dewlng, J.; Davis, D. S. Adw. Catai. 1975, 24, 221. affect the ability of these catalysts to produce methanol Freel, J.; Pleters, W. J. M.; Anderson, R. B. J. Catal. 1969, 14. 247. Haynes, W. "American Chemlcal Industry-A History, Vol. IV 1923-29";Von are the composition of the starting alloys and the extrac- Nostrand Co.;Amsterdam, 1948; p 169. tion procedures used to leach the aluminum and some of Herman, R. G.; Kller. K.; Simmons, G. W.; Finn, 8. P.; Bulko, J. B.; Kobylinski, the zinc from the alloy. T. P. 1979, J. Catai. 1979, 56. 407. Humphreys, 0.C.; Ashman, D. J.; Harris, N. Chem. €con. Eng. Rev. 1974. While the composition of the final catalyst was found 6, 26. to be a function of both the initial alloy compositon and Nadlrov, N. K.; Ashirov, A. M.: Savel'ev, A. F.; Zhusupova. A. 2.flz. Khim. 1977, 51, 1422. the extraction conditions, an alloy composition range for Schermuiy, 0.;Luft, G. Chem. Ing. Techn. 1977, 49, 11. optimal methanol synthesis catalysts was found to be Supp, E., Chem. Tech., 3, 430 (1973). 33-43 wt copper, 7-17 wt % zinc and 50% aluminum. Vokz. S. E.; Wise, J. J. "Development Studies on Conversion of Methanol and 7% Related Oxygenates to Gasoline", 1978, Final Report, ERDA ERDA E(40- Conditions of extraction were found to have marked in- 18b 1773. fluence on selectivity. In general, catalysts prepared under Zahner, J. C. (to Mob11 Oil Corp.), U.S. Patent 4 011 275, Mar 8. 1977. more severe the conditions exhibit higher selectivity and activity for methanol synthesis. Received for reuieu January 16, 1980 It is apparent that considerably more research is re- Accepted June 26, 1980 quired into these catalysts, first into the quite complex area Support was provided under the National Energy Research, of alloy extraction and secondly into their industrial ap- Development and Demonstration Program administered by the plicability with regard to poisoning and thermal stability, Commonwealth Department of National Development. Steam Cracking of Hydrocarbons. 3. Straight-Run Naphtha Martin Bajus and VBclav Veselg Department of Chemistry and Technology of Petroleum, Slovak Technical University, Bratislava, Czechoslovakla Plet A. Leclercq and Jacques A. Rljks' Laboratory of Instrumental Analysis, Elndhoven University of Technology, Eindhoven, The Netherlands Steam cracking of straight-run naphtha from Romashkino crude oil was investigated in quartz and stainless steel reactors with a relatively large ratio of Inner surface to volume. The experiments were performed at atmospheric pressure at 780-800 OC for starting ratios of steam to naphtha between 0.5 and 1.0, with residence times of 0.1-0.4 s. The influence of the reactor material, the temperature, the ratio of steam to hydrocarbon, the residence tlme, and the presence of sulfur compounds is discussed in terms of coke formation and yields of various reaction products. The reaction products were analyzed by gas chromatography, using packed columns for the analysis of the gaseous products and capillary columns for the liquid products. About 200 compounds were identified in the liquid mixture. Reference standard hydrocarbons, published retention data, and mass spectrometry were used for the identifi&tiOn. Introduction Brown and Albright, 1976), propane (Brown and Albright, In the pyrolysis of individual hydrocarbons and petro- 1976; Crynes and Albright, 1969; Tamai and Nishiyama, leum fractions to desired olefins, not only primary reac- 1970; Dunkleman and Albright, 1976b),butanes (Hurd and tions but also secondary reactions occur. Many products Pilgrim, 1933), heptane (Melikadze et al., 1975; Bajus et of splitting, dehydrogenation, hydrogenation, and con- al., 1979a), methylcyclohexane (Bajus et al., 1979b),ethene densation reactions are formed. The composition of the (Brown and Albright, 1976; Hurd and Eilers, 1934), product mixture is influenced by the reaction conditions. propene (Hurd and Eilers, 1934; Ghaley and Crynes, 1976), Important factors are also the type of reactor, the prop- methylpropene and its dimers, and 2-pentene (Hurd and erties of the construction material, the ratio of inner Eilers, 1934) has been investigated. Nonmetallic materials surface to volume, and the activation or passivation of the (glass, quartz, porcelain), metals (iron, nickel, gold, silver, inner surface of the reactor by chemical compounds. The cobalt, titanium), alloys (monel, ascoloy, incoloy 800),and pyrolysis of ethane (Dunkleman and Albright, 1976a; stainless steel of different compositions were used as re- 0196-4 2118011219-0556$01.0010 0 1980 American Chemical Society Ind. Eng. Chem. Prod. Res. Dev., Vol. 19, No. 4, 1980 557 actor materials in these studies. ;; 10 VI 4 The properties of a reaction system, consisting of a I stainless steel reactor with relatively large inner surface, I were investigated in the steam cracking of heptane (Bajus et al., 1979a) and methylcyclohexane (Bajus et al., 1979b). k In this system the thermal decomposition of C7 hydro- a LL carbons proceeded with a relatively low activation energy z!- of about 200 kJ mol-'. The influence of the inner surface uw z on the selectivity of the conversion was reflected in a re- u0 duced yield of methane and ethane. Since high molecular products and coke were absent, it was supposed that either they are not formed or, more probably, they reacted under the influence of the reactor wall with steam to produce carbon monoxide and hydrogen. The presence of sulfur compounds is supposed to cause passivation of the inner surface as a consequence of the formation of a sulfide protection film. It has been shown that the continuous dosage of elemental sulfur together ow) 0% om 022 026 ON ox with the hydrocarbon feed influences the rate and the RESIDENCE TIME [ s I selectivity of the conversion and the formation of coke, Figure 1. Effect of the residence time on the concentration of whereby these effects depend to a large extent on the alkanes in the liquid product mixture from the steam cracking of properties of the surface (Bajus and Vesely, 1979). straight-run naphtha in a stainless steel reactor at 780 OC: (0) Proceeding from the above results, we investigated the pentane; (a)methylbutane; (0) hexane; (0)isohexanes; (e) heptane; (0)isoheptanes; (@) octane; (e) isooctanes. steam cracking of straight-run naphtha in stainless steel and quartz reactors. The influence of the reactor material, coated with squalane. The same column was used in the temperature, the feed ratio of steam to hydrocarbon, GC/MS analysis (Leferink and Leclercq, 1974). The re- the residence time, and the presence of sulfur compounds tention indexes were determined with a precision corre- on the yields of various reaction products is discussed in sponding to a standard deviation of less than 0.5 index this paper.