Energy isobutane alkylation

In this work, the goal is to design a control function in such a manner that neither the reaction heat nor kinetic nor mass transfer terms are required for stabilizing temperature. The scheme provides an estimated value of the heat generation from energy balance. Alkylation isobutane/propylene using sulfuric... 

The relative location of refinery and acid plant is one of the most important factors in the economic decision between sulfuric acid and anhydrous hydrogen fluoride as a catalyst for alkylation. Besides the distance, other factors such as regeneration of spent acid, energy costs, the nature of the feed and increasingly stringent regulatory constraints play an important role in the selection of alkylation catalyst. Sulfuric acid is selected for alkylation if feed is rich in pentenes or n-butene. HF is selected if the feed is rich in propenes or isobutane. 

In each compartment, the pressure is regulated so that some of the dispersed hydrocarbons vaporize. Light hydrocarbons and especially isobutane vaporize this vaporization removes most but not all of the following heats of reaction plus energy provided by agitation. Ackerman et al. have reported that there is a temperature increase from the first to the last compartment simultaneously, the quality of the alkylate decreases.The vaporization, with high certainty, occurs mainly in those droplets positioned at or near the top surface of the dispersion, where the pressure is lowest. Hence, many of the droplets that pass over the vertical plate from one compartment to the next have experienced vaporization (and have reduced concentrations of isobutane). 

Several alkylation reactions with extremely high energy requirements have also been observed over zeolites. Small amounts of toluene and ethylbenzene, together with light paraffin gases, were observed in the alkylation of benzene with isobutane over REX catalyst at 371°. In a reaction that involved fragmentation of the benzene ring, Frilette and Rubin (129) observed the formation of toluene and ethylbenzene when benzene alone was passed over H-mordenite at 400°. 

From this value and known C—H bond dissociation energies, pK values can be calculated. The electrochemical measurements can be made on halides or on alkyl-lithium compounds. This type of approach has some significant uncertainties but nevertheless can provide a least a semiquantitative estimate of acidities of very weakly acidic hydrocarbons. The pK for isobutane obtained in this way is 71. The necessary electrochemical measurements cannot be made directly for methane, but an extrapolation from toluene and diphenylmethane leads to a range of 52-62 for the pK of methane. ... 

Kumar, P. Vermeiren, W. Dath, J.-P. Hoelderich, W. F. (2006). Alkylation of Raffinate II and isobutane on naflon silica nanocomposite for the production of isooctane. Energy Fuels, 20,481-487, ISSN 0887-0624. 

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