Alpha-select process

The Alpha Select process based on metallocene catalysis... 

The last, the Alpha Select process, was introduced to satisfy the demand for plasticizer olefins, which was growing faster than the detergent olefins. 

What is the main difference in results between the Ziegler process and the Alpha Select process ... 

The Ziegler process produces the full range of alpha olefins, from C4 to C2o The Alpha Select process produces C4 through Cio-... 

Description Polymer-grade ethylene is oligomerized in the liquid-phase reactor (1) with a catalyst/solvent system designed for high activity and selectivity. Liquid effluent and spent catalyst are then separated (2) the liquid is distilled (3) for recycling unreacted ethylene to the reactor, then fractionated (4) into high-purity alpha-olefins. Spent catalyst is treated to remove volatile hydrocarbons and recovered. The table below illustrates the superior purities attainable (wt%) with the Alpha-Select process ... 

Ethylene dimerization forming 1-butene can also be carried out selectively with a titanium(IV) derivative which is reduced in situ to titanium(II) (Alpha-butol process, Institut Frangais du Petrole). The result has been attributed to the formation of a titanacyclopentane, which decomposes to 1-butene. The absence of a hydride species active in oligomerization would account for the high selectivity (Figure 15). No additional solvent is required, as 1-butene also acts as solvent. The total world butene production capacity by this process is estimated to be >300 kt/a. 

Another unintended consequence is illustrated by Alpha s choice of investment projects. Alpha, by virtue of its project selection process, is likely to pick project "A." That project shows a good return on investment, has a strong advocacy, and represents the "path of least resistance" for management. But it has the risk of providing only minor improvement — in spite of all the safeguards put in place to protect the corporate pocketbook. 

Olivier-Bourbigou Lecocq, 2003) Chloroaluminate ILs and Ni(COD)(2) with a Bronsted acid ILs Biphasic ethylene oligomerization or butene and higher olefins dimerization (Difasol process). These solvents stabilize and activate nickel catalysts, even without ligand, and greatly enhance the reaction activity. The presence of a diimine ligand allows the production of C4-C6 linear olefins with improved alpha-selectivities. 

The use of a Fischer-Tropsch (FT) process to produce long-chain hydrocarbons is well known in industry, and achieving the desired selectivity from the FT reaction is crucial for the process to make economic sense. It is, however, well known that a one-alpha model does not describe the product spectrum well. From either a chemicals or fuels perspective, hydrocarbon selectivity in the FT process needs to be thoroughly understood in order to manipulate process conditions and allow the optimization of the required product yield to maximize the plant profitability. There are many unanswered questions regarding the selectivity of the iron-based low-temperature Fischer-Tropsch (Fe-LTFT) synthesis. 

The book focuses on three main themes catalyst preparation and activation, reaction mechanism, and process-related topics. A panel of expert contributors discusses synthesis of catalysts, carbon nanomaterials, nitric oxide calcinations, the influence of carbon, catalytic performance issues, chelating agents, and Cu and alkali promoters. They also explore Co/silica catalysts, thermodynamic control, the Two Alpha model, co-feeding experiments, internal diffusion limitations. Fe-LTFT selectivity, and the effect of co-fed water. Lastly, the book examines cross-flow filtration, kinetic studies, reduction of CO emissions, syncrude, and low-temperature water-gas shift. 

The process operates in the liquid phase by dissolving the ethylene in an inert solvent such as cyclohexane or isopentane. The metallocene catalyst is also injected to the mix. The solvent has several important functions. It keeps in solution the alpha olefins produced as well as the ethylene and catalyst. It also enhances the catalyst activity and selectivity. 

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