Olefin conversion oligomerization

It was established that in the presence of the investigated Ni-HMC various factors, such as pressure, temperature, molar correlation Al/Ni do not significantly influence the selectivity of oligomerization process, but the olefin conversion and the yield of product are very dependent on these factors (TableS). 

CO reactants and the H2O product of the synthesis step inhibit many of these secondary reactions. As a result, their rates are often higher near the reactor inlet, near the exit of high conversion reactors, and within transport-limited pellets. On the other hand, larger olefins that are selectively retained within transport-limited pellets preferentially react in secondary steps, whether these merely reverse chain termination or lead to products not usually formed in the FT synthesis. In later sections, we discuss the effects of olefin hydrogenation, oligomerization, and acid-type cracking on the carbon number distribution and on the functionality of Fischer-Tropsch synthesis products. We also show the dramatic effects of CO depletion and of low water concentrations on the rate and selectivity of secondary reactions during FT synthesis. 

Low temperature (100-250°C) conversion of olefins, notably oligomerization and alkylation, is made possible by involving cracking reactions to clean up the pore system [4] or to operate at very low olefin concentrations to prevent formation of deposits [5], respectively. Processing of olefins in the temperature range of say 300-500°C at high partial pressures of olefins is even more difficult. Skeletal isomerization of olefins and aromatisation of olefins are examples of desired reactions in this temperature range. 

Sulfate-activated Ti02 and Zr02 or a molecular sieve (LZ-Y52, 4A, AW-500, and AW-300) were used in the oligomerization of Cio-20 alkenes. Olefin conversion was 64% and dimer/trimer ratio 5.57, and 86% and 1.80 for sulfated Ti02 and Zr02, respectively. The AW-sulfate activated molecular sieve showed higher activity in comparison with the other molecular sieves. 

Methanol To Gasoline) and MTS (Methanol To Synfuel), the production of fuels by oligomerization of olefins (Conversion of Olefins to Distillate, COD) or the synthesis of a wide range of hydrocarbons in Fischer-Tropsch processes. Some main features of these processes are outlined in the following sections. 

This reaction occurred in all cases of ethylene-higher a-olefin oligomerization the added a-olefin was partially isomerized to cis- and trans-2-olefins. Conversions in these isomerization reactions varied from 2.5 to 6%. Cis- and trans-2-olefins with linear chains are also formed in ethylene homooligomerization reaction [227]. Their presence in ethylene oligomers can be similarly explained as a secondary reaction (reaction 81) with the participation of the ethylene oligomers. Olefins with other internal double bonds cannot be formed in reaction (14) from a-olefins. Their possible formation from other olefins with internal double bonds (e.g., formation of 3-olefins from 2-olefins, etc.) in reactions analogous to reaction... 

The direct methane conversion technology, which has received the most research attention, involves the oxidative coupling of methane to produce higher hydrocarbons (qv) such as ethylene (qv). These olefinic products may be upgraded to Hquid fuels via catalytic oligomerization processes. 

Olefins with a-C—H bond, which is easily attacked by the peroxyl radical, are oxidized in parallel to hydroperoxide and oligomeric peroxide [108,109]. The competition between these two routes of oxidation was studied by Hargrave and Morris [92] (333 348 K, conversion 0.1 0.2 wt.%) ... 

The patent literature contains several references to the use of sulfoxide complexes, usually generated in situ, as catalyst precursors in oligomerization and polymerization reactions. Thus, a system based upon bis(acrylonitrile)nickel(0> with added Me2SO or EtgSO is an effective cyclotrimerization catalyst for the conversion of butadiene to cyclo-1,5,-9-dodecatriene (44). A similar system based on titanium has also been reported (407). Nickel(II) sulfoxide complexes, again generated in situ, have been patented as catalyst precursors for the dimerization of pro-pene (151) and the higher olefins (152) in the presence of added alkyl aluminum compounds. 

Double bond isomerization using molecular sieves (5A) was reported in the patent literature by Fleck and Wight of Union Oil Company [34] only a few years after synthetic zeolites became commercially available. More recently [35] ferrierite has also been claimed. The major initial uses were to convert a-olefins (1-olefins) into mixtures of internal olefins for further conversion, usually by oligomerization into various products-lube oil base stocks predominating. Inevitably, patents were issued noting the ability to convert internal olefins into mixtures containing greater concentrations of 1-olefins (e.g., [36]), but few practical processes have resulted. 

Additional uses for higher olefins include the production of epoxides for subsequent conversion into surface-active agents, alkylation of benzene to produce drag-flow reducers, alkylation of phenol to produce antioxidants, oligomerization to produce synthetic waxes (qv), and the production of linear mercaptans for use in agricultural chemicals and polymer stabilizers. Aluminum alkyls can be produced from heavy olefin streams and olefin or paraffin streams have been sulfaled or sulfonated and used in the leather (qv) industry. 

Propylene and other olefins of higher molecular weight can be easily oligomerized over a wide range of zeolitic and nonzeolitic acid catalysts.[1114] However, in the case of ethylene only low conversions can be obtained over acidic catalysts. Transition metal catalysts, on the other hand, and particularly those based on Ni... 

Another way to improve the regio- and stereospecificity in the conversion of a-olefins is to carry out oligomerization with metallocene catalysts. Under... 

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