Industrial processes dimersol

Showing so much promise it is not surprising that ionic liquids are already used within large-scale industrial appUcations and that further industrial processes are in development. The Dimersol/Difasol process developed by the Institut Francais du Petrole uses an ionic Uquid to dissolve the catalyst and to separate the catalyst phase from the product [19]. The products of the reaction—C 8 olefins—are not soluble in the ionic Hquid and form a second phase that can be easily separated. The nickel catalyst dissolved in the ionic liquid can be recycled. In addition, the catalyst shows in the ionic Hquid increased activity and better selectivity to the desired dimers rather than to the undesired higher oUgomers. 

Another example is butene dimerization catalyzed by nickel complexes in acidic chloroaluminates 14). This reaction has been performed on a continuous basis on the pilot scale by IFF (Difasol process). Relative to the industrial process involving homogeneous catalysis (Dimersol process), the overall yield in dimers is increased. Similarly, selective hydrogenation of diene can be performed in ionic liquids, because the solubility of dienes is higher than that of monoene, which is higher than that of paraffins. In the case of the Difasol process, a reduction of the volume of the reaction section by a factor of up to 40 can be achieved. This new Difasol technology enables lower dimer (e.g., octenes) production costs 14). 

A similar catalytic process (Dimersol, Institut Frangais du Petrole), based on a nickel hydride formed in situ from a nickel complex and an aluminium alkyl, has been applied industrially to oligomerize ethylene, propylene, butenes or mixtures of the three. 

The liquid-phase industrial process for the dimerization of propylene is called the dimersol process. In this process, a Zeigler-type catalyst is generated in situ by the treatment of a nickel salt with trialkyl aluminum. The different isomers of C. alkenes that are formed can be explained by referring to Figure 7.1. A nickel hydride complex 7.1 initiates the dimerization reaction. Complexes 1.1 and 73 are formed by the insertion of the first propylene into the Ni-H bond in anti-Markovnikov and Markovnikov maimer, respectively. 

The new Difasol process for manufacturing isooctenes consumes less catalyst. The process dimerizes n-butene in a continuous two-phase operation that uses the industrial Dimersol nickel catalyst dissolved in a chloroaluminate ionic liquid. The n-bu-tenes are introduced continuously into the reactor, and the products are only poorly miscible with ionic liquid, and separate in settler. The process shows 70-80% conversion with 90-95% selectivity (Freemantle, 1998). 

The ionic liquid can, for example, be added to the butene effluent from the Dimersol process to obtain octenes by butene dimerization the octene can be carbonylated (Section 4.6) and hydrogenated to wo-nonanol, used to make phthalate plasticizers. In the case of the Phillips trimerization process the use of an ionic liquid allows an easy separation of the trimers and the catalyst for recycling (see also reviews to Section 5.5). However, the industrial use as solvents of ionic liquids, containing halide species (especially anions such as Bp4, PFg, or AlCU ) has the disadvantage that they readily break down to give HX, which can adversely affect the reaction. New types of non-halide containing ionic liquids are being actively researched. 

Improvements in existing processes accompagnied by new techniques. The first edition of this book presented 70 processes. It now discusses 140. Admittedly these are not all innovations. Many of them are different versions of the same chemical reaction or of an already existing separation method. Others, more innovative, only made headway slowly their industrial penetration was hindered by the slowdown in economic expansion new solvents in extractive distillation for benzene production, metathesis of olefins (Shell), olefins for oxo synthesis (Dimersol, Instituc Franfais du Pitrole), adiponitrile by direct hydrocyanation of butadiene (Dm Pont de Nemours), or by the conversion of 1,6-hexanediol (Celanese), laur IIactam from cyclododecane [ATO, Huls). 

Nonregioselective dimerization is widely used on an industrial scale for propene, n-butenes and ethylene (Institut Fran9ais du Petrole s Dimersol process). The catalyst results from the interaction of a nickel organic salt, soluble in a paraffinic hydrocarbon solvent, and an ethylaluminum chloro compound the active species is formed in situ inside the dimerization reactor. 

The range of homogeneous reactions that has been transposed into ILs is probably wider than into SCCO2 or perfluorinated solvents due to the great versatility of ILs. However, most of these reactions are limited to laboratory- or bench-scale with just a few examples of pilot-scale. A relevant industrial example is the Difasol process, which can be seen as an extension of the Dimersol family of processes developed by IFP [94] ... 

Dimerization of re-butenes in an ionic liquid serves as basis for the new Di-fasol process for manufacturing isooctene with conversion between 70% and 80% and a very high selectivity to 90-95% of octenes. The continuous two-phase process uses the industrial Dimersol nickel catalyst dissolved in a chloroaluminate ionic liquid obtained in reaction of AICI3 and dialkylimidazolium chlorides. The ionic catalyst is retained in the IL phase that can be easily separated from the less dense organic phase of products and unreacted butenes. An important feature of the process that it works efficiently even with feeds of low butene content which makes it suitable to integrate with existing Dimersol plants. The process has been successfully operated in a pilot plant (282,285). 

The hydroformylation of mixtures of Cg-olefins is a process with huge economic importance. A typical example is di-n-butene, consisting of isomeric -octenes, methylheptenes, and dimethylhexenes. The mixture is produced from Raffinate II, in which isomeric butenes are dimerized (e.g., by IFP Dimersol [47] or Octol process [48]). Hydroformylation of di- -butene produces linear and alkyl-branched Cg-aldehydes, which are converted to diisononyl phthalate (DINP), another additive for flexible PVC with immense industrial relevance. For this application, the use of terminal aldehydes is preferred. 

Pilot-scale as well as industrial-scale (IFF dimersol process) oligomerization of propylene using organometallic catalysts have been reported [540,541]. The... 

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