Catalytic Cracking of Heavy Olefins into Propylene, Ethylene and Other Light Olefins
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Catalytic Cracking of Heavy Olefins into Propylene, Ethylene and Other Light Olefins R. Le Van Mao Æ A. Muntasar Æ H. T. Yan Æ Q. Zhao
Received: 12 January 2009 / Accepted: 17 February 2009 / Published online: 4 March 2009 Ó Springer Science+Business Media, LLC 2009
Abstract Hybrid catalysts developed for the thermocatalytic cracking of liquid hydrocarbons were found to be capable of cracking C4? olefins into light olefins with very high combined yields of product ethylene and propylene (more than 60 wt%) and C2–C4 olefins (more than 80 wt%) at 610–640 °C, and also with a propylene/ethylene weight ratio being much higher than 2.4. The olefins tested were heavier than butenes such as 1-hexene, C10? linear alphaolefins (LAO) or a mixture of LAO. The hydrogen spillover effect promoted by the Ni bearing co-catalyst, contributed to significantly enhancing the product yield of light olefins and the on-stream stability of the hybrid catalyst. Keywords TCC-type hybrid catalysts Cracking of heavy olefins Effect of hydrogen spillover on product yields and coke deposition
1 Introduction Light olefins, particularly the high-volume produced ethylene and propylene, are the backbone of the petrochemical industry [1]. Ethylene and propylene are experiencing continuous growth due to a sustained worldwide demand. However, in recent years, propylene is booming on the demand site [2], so that the industry has to move this intermediate from the state of by-product of the
R. Le Van Mao (&) A. Muntasar H. T. Yan Q. Zhao Industrial Catalysis Laboratory, Department of Chemistry and Biochemistry, Concordia University, 7141 Sherbrooke West, SP 275-09, Montreal, QC H4B 1R6, Canada e-mail: [email protected]
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hydrocarbon steam cracking (SC) into that of one of the main products. Thus, several processes are being used for an increasing production of propylene, such as propane dehydrogenation, olefin metathesis and mostly (modified) fluid catalytic cracking (FCC). The thermo-catalytic cracking process (TCC) of various liquid hydrocarbon feedstocks (naphthas, gas oils) has been recently developed with the main objective to produce ethylene and propylene, the product propylene/ethylene weight ratio being higher than that obtained by the conventional steam cracking [3–6]. In addition, the TCC process shows some other important technical and environmental advantages (lower reaction temperatures and less carbon deposition on the reactor walls) [5, 6]. The most recent version of the TCC catalysts possesses a hybrid configuration that comprises of a main component and a co-catalyst [5, 6]. The role of the main catalyst component is to crack large hydrocarbons of the feed over the cracking sites provided by the (Mo–P) species while the resulting smaller molecules are subsequently cracked onto the (ZSM-5) zeolite acid sites [5]. The co-catalyst contains a noble metal (Pt or Pd) or Ni being dispersed on a very hydrothermally stable support [5–7]. The role assigned to the co-catalyst is to prevent or slow down the currently rapid for
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