Olefin synthesis
Sajjad Bahrami Reyhan; Seyed Mahdi Alavi; Davood Soudbar
Abstract
Ethylene dimerization is a significant process among the other petrochemical processes due to the production of alpha olefins as the most widely used industrial intermediate. Titanium tetra butoxide/tetrahydrofuran/triethyl aluminum is the main homogeneous catalyst complex in this process. On the other ...
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Ethylene dimerization is a significant process among the other petrochemical processes due to the production of alpha olefins as the most widely used industrial intermediate. Titanium tetra butoxide/tetrahydrofuran/triethyl aluminum is the main homogeneous catalyst complex in this process. On the other hand, the formation of polymer or oligomerization side reactions are the salient obstacles in the ethylene dimerization process. The effect of various promoters from the group of halo hydrocarbons, along with different modifiers from the group of esters and silane compounds had been investigated to conquer the barriers mentioned above. The reaction conversion, selectivity, and polymer production were the remarkable parameters that were evaluated to study the components’ impacts. The results indicated that the addition of promoters through reaction with Triethyl aluminum (TEA) (co-catalyst) increased the reaction speed and thus increased the conversion of the reaction to 88.26% and reduced the reaction time to 60 min. Among the promoters, the reaction conversion and selectivity of dichloromethane were 88.26% and 78.45%, higher than that of dibromopropane (48.52% and 39.52%), but a higher amount of polymer was produced by dichloromethane. Moreover, Esters strongly decreased the catalyst activity, resulting in a decrease in the conversion to under 25%. On the other hand, silanes showed a significant effect on the control of the polymer chains in Ziegler-Natta homogeneous catalysts. Dicyclopentyldimethoxysilane (DCPDS) modifier brought about an increase of 1.5% in ethylene conversion and a 6% increase in the 1-butene selectivity. At the same time, the polymer formation also prevented a significant amount so the amount of polymer decreased to about 2.1 mg. DCPDS modifier performed better than the Cyclohexylmethyldimethoxysilane (CHMDS) donor.
Olefin synthesis
Salman Beyraghi; Mohammad Rostamizadeh; Reza Alizadeh
Abstract
Methanol dehydration is a high potential route for the production of light olefins (C2-C4). In this study, hierarchical Si-rich [B]-ZSM-5 catalysts (Si/Al= 200) were prepared through one-pot hydrothermal synthesis, including boron as a promoter and ethanol as a low-cost secondary template. N2 adsorptiondesorption, ...
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Methanol dehydration is a high potential route for the production of light olefins (C2-C4). In this study, hierarchical Si-rich [B]-ZSM-5 catalysts (Si/Al= 200) were prepared through one-pot hydrothermal synthesis, including boron as a promoter and ethanol as a low-cost secondary template. N2 adsorptiondesorption, XRD, FE-SEM, and FT-IR techniques were applied to characterize the catalysts. The effect of different amounts of ethanol and different operating conditions was studied on the ZSM-5 catalyst preparation and performance in methanol-to-olefins (MTO) reaction. The results showed that the optimum amount of ethanol (ethanol/TPABr=5) led to the highest crystallinity (91.2%), the highest specific surface area (>400 m2g-1), and total pore volume (0.19 cm3g-1). The best catalytic performance was obtained at temperature of 480°C and methanol hourly space velocity (WHSV) of 7.2 h-1. The optimum catalyst had the highest propylene selectivity (58%) and light olefin selectivity (85%). The results proved the high capability of the new strategy for the efficient and fast development of the MTO catalyst.
Olefin synthesis
Mohamad Hafizi Zakria; Mohd Ghazali Mohd Nawawi; Mohd Rizal Abdul Rahman; Mohd Anas Saudi
Abstract
The research was carried out in a large-scale olefin process to see how different variables affect ethylene yield in an actual fluctuating plant condition. Regression analysis was adopted using Minitab Software Version 18 to create a reliable ethylene yield model. Regression analysis is a robust, practical, ...
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The research was carried out in a large-scale olefin process to see how different variables affect ethylene yield in an actual fluctuating plant condition. Regression analysis was adopted using Minitab Software Version 18 to create a reliable ethylene yield model. Regression analysis is a robust, practical, and advanced tool that is used in various applications as an alternative to the complex, expensive, and restricted simulation software that is specifically designed for the olefin process. The 1688 data taken from the studied plant underwent outliers and residuals removal utilizing normality and stability tools in Minitab for the analysis to be conducted as normal data. The Regression was conducted a few times until all variables satisfactorily met the multicollinearity criteria with Variance Inflation Factor (VIF) < 10 and 95% confidence level criteria with P-Value < 0.05. The final Regression model established 4 significant variables which were Hearth Burner Flow, Integral Burner Flow, Super High- Pressure Steam (SHP) Temperature, and Naphtha Feed Flow by factors of -0.001266, 0.04515, -0.0795, and 0.2105, respectively. The maximum ethylene yield was calculated at 31.75% using Response Optimizer with the recommended operating conditions at 9908.50 kg/h Hearth Burner Flow, 600.39 kg/h Integral Burner Flow, 494.65°C SHP Temperature, and 63.50 t/h Naphtha Feed Flow.
Catalysis
Andrea M. Rimkus; Helmut G. Alt
Abstract
Eight different zirconium phenoxyimine complexes were synthesized, characterized and tested as catalysts for ethylene polymerization. The phenoxyimine compounds were prepared by condensation of substituted salicylaldehydes with aliphatic and aromatic amines, the substituted salicylaldehydes from ortho ...
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Eight different zirconium phenoxyimine complexes were synthesized, characterized and tested as catalysts for ethylene polymerization. The phenoxyimine compounds were prepared by condensation of substituted salicylaldehydes with aliphatic and aromatic amines, the substituted salicylaldehydes from ortho substituted phenols and paraformaldehyde. The introduction of iodo substituents was achieved either by iodination of the aldehyde component followed by condensation with amines or the iodination of the aldehyde after the condensation with amines or the iodination via condensation with iodo substituted amines. Deprotonation of the hydroxy function of phenoxyimine compounds and reaction with zirconium tetrachloride gave mononuclear bis(phenoxyimine) zirconium complexes in good yields. These complexes were activated with methylaluminoxane (MAO) and applied for ethylene polymerization. The performances of the various catalysts were compared and structure-property-relationships were discussed.
