Iranian Journal of Chemical Engineering (IJChE)

Abstract "> The effects of templating on the catalytic performance of SAPO-34 catalyst have been investigated in conversion of methanol to olefins. SAPO-34 catalysts were synthesized using a different combination of morphine, tetraethyl ammonium hydroxide (TEAOH) and triethylamine (TEA) as structure-directing agents during synthesis of gel with nominal composition as 1Al2O3:1P2O5:0.4SiO2:2yTEAOH:2xTEA:2(1-(x+y))morpholine:70H2O. The different SAPO-34 samples were characterized by XRD, SEM, FTIR, BET, EDX and TPD techniques. Increasing TEAOH in synthesis gel led to decreasing mean crystal size. The catalytic performance of the synthesized catalysts was tested in MTO reaction at 410C and a feed WHSV of 6.5 1/h. The catalyst synthesized by combination of tri-templates exhibited highest light olefins yield in 100% methanol conversion. The optimum values (X=0.17, Y=0.34) were obtained by central composite design and response surface contour plots.

Abstract

Abstract The effectiveness of binary mixtures of phosphorus and sulfur compounds as coke inhibitors for naphtha pyrolysis has been studied. As both phosphorus and sulfur compounds proved to be promising coke inhibitors, runs were made with mixtures of these compounds. The coke deposited was significantly lower when phosphor was used together with sulfur. Also, the effect of the addition of K₂CO₃ and K₂CO₃ in the naphtha feed was investigated. It was found that the addition of Na₂CO₃ and K₂CO₃ reduced the coke formation. Scanning electron microscope (SEM) was used for the
microstructure of deposited coke and energy dispersive X-Ray spectroscopy (EDAX) for the surface elemental composition of coke formed on the surface of stainless steel coupons. It was found that in the presence of inhibitors, deposited coke has a porous structure and so small amounts of Ni , Cr , and Fe elements.

Abstract A study on coke deposition and coking inhibitors during naphtha pyrolysis was made in a jet stirred reactor system. This system is noted for its simple structure, easy alteration of operating parameters, small volumes of feedstock used for pyrolysis, high accuracy of coke formation measurements, and short operating cycle. It is also particularly suitable for identifring coking inhibitors over a wide range of conditions. The effect of the addition of CS2, DMS, DMDS and Disulfideoil in the naphtha feed was investigated. It was found that for a given concentration of sulfa. in the feed, the asymptotic coking rate decreases in the order: Dimethyl disulfide > Disulfideoil > Dimethyl sulfide > Carbon disulfide. Scanning electron microscope (SEM) was used for the microstructure of deposited coke and energy dispersive X-Ray spectroscopy (EDAX) for the surface elemental composition of coke formed on the surface of stainless steel coupons. It was found that in the presence of inhibitors, deposited coke has a porous structure and small amounts of Ni, Cr, and Fe elements. Based on our results, this paper aims to provide a closer insight into the coking problem in industrial steam crackers. 

Abstract SHAHAB is a PC- based simulator developed by Olefin Research Group (ORG), with the simultaneous simulation of the reactor, the firebox, the convection section and the transfer line exchanger in steam Cracking units. The reaction mechanism of thermal cracking of hydrocarbons is generally accepted as free-radical chain reactions. Using a rigorous kinetic model, a complete reaction network for representing the decomposition of hydrocarbon feedstocks has been developed and used for simulation of thermal hydrocarbon crackers. Taking into account the kinetics of coke formation, SHAHAB provides a detailed understanding of product, temperature and pressure distribution, coke thickness profile, reactor run length, fuel consumption and the amount of steam generated.