Solid alkylation

Crystalline derivatives of aliphatic nitriles may be prepared by an application of the Hoesch reaction. Equimolecular proportions of phloroglucinol and the nitrile react in dry ethereal solution in the presence of anhydrous zinc chloride and hydrogen chloride to give an imine hydrochloride, which is converted into a solid alkyl trihydroxyphenyl ketone by hydrolysis. The alkyl 2,4,6-trihydroxy-phenyl ketones are usually highly crystalline solids of sharp melting point and are purified by recrystallisation from hot water. Many contain water of crystallisation which can be removed by drying in vacuo at about 100 °C the melting points of both the hydrated and anhydrous compound should be determined. 

Table II. Comparison of Capital and Operating Costs of Liquid and Solid Alkylation Technologies...

Nevertheless, there is no doubt that it would be highly desirable to find an alternative to the actual alkylation technology, based on a new process which relies on nontoxic, easy-to-handle, environment friendly catalysts. Along this line, much effort has been devoted in the past 30 years to find an appropriate solid alkylation catalyst that is resistant to deactivation and can produce good... 

From previous works, it becomes clear that, with the exception of the onedimensional ZSM-12 zeolite mentioned above, large-pore zeolites with three-dimensional pore structures such as faujasite (X and Y) and beta are more appropriate as solid alkylation catalysts because of the easiest formation and diffusion of the desired TMP products and improved lifetime. Among them, beta has been shown to outperform USY, particularly in terms of catalyst lifetime (117). At equivalent reaction conditions (T = 50°C, P = 20 bar, isobutane-to-olefin ratio (I/O) = 15, olefin WHSV = 1 h ), zeolite beta displays a lower deactivation... 

Faujasites exchanged with rare earth cations, and particularly with La " ", have shown good performance as solid alkylation catalysts, as nicely reported in the pioneering works carried out in the late 1960s by researchers at Mobil Oil (89) and Sun Oil (96), and later on by Weitkamp s group (132,133). This fact is most likely related to the ability of La-FAU zeolites to catalyze hydride transfer reactions. The Bronsted acidity in La-exchanged FAU zeolites can be associated with the protons generated upon hydrolysis of water in the hydrated lanthanum cations when snbjected to thermal activation treatment at temperatures between 60 and 300°C (134-136) ... 

Fixed bed and liquid riser type reactors are found in the majority of the proposed commercial solid acid alkylation processes, as will be detailed hereinafter. Nevertheless, other reactor configurations have been proposed for alkylation processes employing solid catalysts. For instance, a spouted bed reactor is constituted by a gas flow propelled riser, an annular downcomer where part of the solid and liquid are recycled to the reactor inlet and a hydrocyclon in which the solid catalyst is collected to be regenerated in continuous at a neighboring unit. Recently, a spouted bed reactor equipped with a fluidized-bed catalyst regenerator has been designed to be used in solid alkylation processes, employing a Pt/S0x(Zr-Ti)02... 

Lurgi, in collaboration with Siid-Chemie, developed a solid alkylation process based on a reactive distillation reactor (241). The distillation trays are used as reaction steps, with lateral staged olefin feed, and the catalyst pellets are not fixed but slurried within the liquid hydrocarbons. Vaporization of the reactive mixture at the bottom of the column reactor is used to dissipate the heat of reaction while it provides a rising vapor, which favors the required turbulence for a good mass transfer in the multiphase system. Recent sources indicated that the process is not commercially offered at the moment. 

Several applications of the in situ decoking concept have appeared in the literature. One such application involves stabilizing the activity of solid acid catalysts such as in alkylation reactions. As reviewed elsewhere (55), numerous efforts aimed at developing solid acid alkylation catalysts and solid acid-based isobutane-olefin alkylation processes have been reported for more than three decades. However, to date, none of the solid alkylation catalysts has gained acceptance in industry for one or more of the following drawbacks rapid catalyst... 

Because of the expanding role of alkylate in reformulated fuels, new developments are currently being pursued. This includes more stable, solid alkylation catalysts, improved liquid catalysts and two stage processes which produce higher octane product (Albright, 1990). 

December 1998 A process is described for alkylating an isoparaffin and an olefin with a solid alkylation catalyst in an inert solvent where the reaction mixture is under SCF conditions. 

A process is disclosed for alkylating a volatile aromatic compound with an aliphatic olehn over a solid alkylation catalyst above the critical point of the reactant mixture. 

Nitriles are liquids or low melting solids. Alkyl cyanides usually have moderate water-solubility, while aryl qranides are sparingly soluble in water and some smell of almonds. 

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