Showing papers in "Preprints-American Chemical Society Division of Petroleum Chemistry in 1988"

The framework topology of zeolite beta

Abstract: The tetrahedral framework structure of zeolite beta is disordered along (001). The disordered structure is related by a/3 and/or b/3 displacements on (001) planes to three ordered polytype structures with triclinic, monoclinic, and tetragonal symmetry. Three mutually perpendicular 12-ring channel systems are characteristic of the three ordered polytypes and the disordered beta structure. The proposed framework structures are consistent with the known diffraction, sorption an cation exchange properties of zeolite beta.

Detailed chemical kinetic modeling of butylbenzene pyrolysis

Abstract: A chemical kinetic model was constructed for the pyrolysis of butylbenzene. The mechanism was based on free radical reactions. All relevant reactions were considered, and a final selection of 60 reactions involving 29 molecules and free radicals was made. The rate constants and thermodynamic parameters were taken from the literature or estimated using accepted literature methods such as group additivity. The results from the model were compared to experimental rates and product selectivity for butylbenzene pyrolysis over a temperature range of 778 K to 868 K and to an experimental rate at 923 K. The rates agreed within a factor of two and were usually much closer. The experimental and theoretical yields of the major products, styrene, ethane, toluene, and propylene, agreed within two percentage points. The agreement for seven minor products was not quite as good, with the worst case being an overprediction of the yield of allylbenzene by a factor of 2.6.

The structure of the cobalt sulfide phase in carbon-supported Co and Co-Mo sulfide catalysts as studied by EXAFS and XANES

Abstract: Les resultats des analyses structurales sont utilises pour etudier l'activite des catalyseurs au cours d'hydrodesulfuration

The application of laboratory-scale catalytic fixed and fluidized bed reactors in the oxidative coupling of methane

Abstract: The oxidative coupling of methane with oxygen has received increasing attention during the last few years. The experiments which have been reported for continuous operation (cofeed method) have been carried out in different laboratory-scale reactors. One of the earliest catalysts resulting in appreciable C/sub 2//sup +/ selectivities consisted of PbO as catalytic compound supported by /gamma/-Al/sub 2/O/sub 3/; C/sub 2+/ selectivities amounted to approximately 60% using methane to oxygen ratios in the order of 10 at 700 to 750/degree/C. Higher methane to oxygen ratios lead even to better C/sub 2+/ selectivities (70%) but lower methane conversions. The optimum PbO loading on the /gamma/-Al/sub 2/O/sub 3/ support resulting in maximum C/sub 2+/ selectivities was in the order of 30 to 36 wt.-%. Subsequent studies revealed that support acidity affect significantly and selectivity; basic supports improved C/sub 2+/ selectivites. Furthermore, basic catalysts consisting of alkali and alkaline earth compounds and their respective mixtures resulted in even higher selectivities of up to 90% depending on reaction conditions. Most of these alkali/alkaline earth compound catalysts deactivated with time-on-stream. A NaOH/CaO catalyst showed only little deactivation during 160 hours of time on stream; C/sub 2+/ selectivities were in the order of 75% using a methanemore » to oxygen ratio equal to 9. In the present paper results obtained during long-time operation are reported for a PbO (36 wt.-%)//gamma/-Al/sub 2/O/sub 3/-supported catalyst and a NaOH (11 mole%)/CaO catalyst used in an isothermal micro catalytic fixed bed reactor, a non-isothermal catalytic fixed bed and an isothermal fluidized bed reactor.« less

A microscale simulation test for FCC development

Abstract: L'optimisation de la simulation du craquage catalytique fluide en laboratoire conduit a interpreter les resultats en terme d'influence des conditions operatoires dans le reacteur sur la cinetique de craquage. Le role des composes aromatiques est determine

Characterization and C5/C6 isomerization activity of solid superacid (Pt/SO42-/ZrO2)

Abstract: Etude de la preparation des proprietes physico-chimiques et de l'activite du catalyseur Pt/SO 4 2− /ZrO 2 au cours de l'isomerisation du n-heptane. Sa stabilite a long terme est determinee

Light-off temperature determination of oxidation catalyst using FTIR technique

Abstract: La temperature d'oxydation et les produits de reaction sont determines par spectrometrie FTIR in situ. Les performances de trois catalyseurs trois voies sont determinees ainsi que l'energie d'activation de la formation du monoxyde et du dioxyde de carbone

Ceramic membranes for studies of reaction and diffusion

Abstract: The authors present here a brief overview of our ongoing research studies of reaction and transport through porous ceramic membranes. Ceramic membranes are a new class of materials offering great promise for a wide range of catalytic and bioengineering applications. Our fundamental knowledge, however, of transport and reaction phenomena through porous membranes still remains very incomplete and currently presents a major stumbling block in the wider industrial applicability and acceptance of these materials.

Dependence of Reaction Pathways and Product Distribution on the Oxidation State of Palladium Catalysts for the Reactions of Olefinic and Aromatic Substrates with Molecular Oxygen

Abstract: Palladium chemistry dominates the catalytic liquid phase oxidation of unsaturated hydrocarbons both in the breadth of commercial processes and in the large number of synthetic applications Recent work has shown the potential for new routes via oxygen activation chemistry Control of the oxidation state of Pd catalysts can provide new routes to ally lie oxidation products Routes to industrially important a,β-unsaturated alcohols, esters and acids occur via both Pd(IV) and Pd(0) intermediates High oxidation state palladium complexes are implicated in selective catalytic aromatic ring oxidations, while Pd(II) intermediates give rise to oxidative coupling, and low oxidation state species are responsible for benzylic oxidations

Protocol development for evaluation of commercial catalytic cracking catalysts

Abstract: Un protocole d'essai a ete developpe pour caracteriser les catalyseurs de craquage catalytique fluide utilises dans les unites de craquage Ashland. Il consiste en tests de microactivite, en essais en laboratoire et dans des unites pilotes

Attrition resistant microporous particles by spray drying

Abstract: Industrial powders made of grains in the micron size range are often used in processes that require high attrition resistance. Good examples of such powders are catalysts for fluid bed processes which are generally made of ca. 45 to ca. 150 or 200 {mu}m porous grains, hereby referred to as porous micrograins or, if they are spheroidal, porous microspheres (PMS). A conventional approach to impart attrition resistance to a catalyst grain is to embed small particles of the active catalyst in a continuous framework or skeleton made of a hard and relatively inert material. In this case, the percentage of hard materials required to impart sufficient attrition resistance to the catalyst composite particle is so high ({approximately} 50%) that it may affect the activity and/or the selectivity of the catalyst.

Characterization of petroleum feedstocks by TG-FTIR

Abstract: For the characterization of hydrocarbons, thermogravimetric (TG) analysis techniques have proved very useful. However, TG analysis by itself does not identify the decomposition products. When TG analysis is coupled with evolved product analysis by FT-IR, a wealth of information regarding the composition of pyrolysis and oxidation products is obtained. The application of TG-FTIR to coal and petroleum source rock has been described in two recent publications. The most difficult to analyze effluents are the heavy decomposition products which condense at room temperature. These condensates such as tars from coal, asphaltenes and pre-asphaltenes from petroleum or coal derived liquids, and oligomers from polymers are invariably the major evolved products from most hydrocarbons. Their amount and composition are important in predicting the behavior of the hydrocarbon in an upgrading or conversion application. A recently designed apparatus, the Bomem TG/Plus, which combines a DEUPONT 951 TGA with a multi-pass gas cell and a MICHELSON FT-IR provides a standard TG analysis while simultaneously monitoring these condensible products as well as gases. The purpose of this paper is to describe the application of the TG/PLUS for the analysis of heavy hydrocarbons.

Coke forming reaction kinetic study on petroleum based feeds

Abstract: Developpement d'un modele cinetique qui permet de decrire les mecanismes de cokefaction en modelisant la conversion de la matiere volatile en coke non fusible

Non-aqueous spray during as a route to ultrafine ceramic powders

Abstract: Spray drying imparts unique powder handling features to a wide variety of dried products and is usually carried out in a heated air stream while feeding an aqueous suspension of some solid material. The present work, however, describes non-aqueous spray drying as a means of preparing fine powders of metal oxides. In this case an alcohol solvent was used in place of water and the slurry sprayed under an inert atmosphere. Using the non-aqueous technique, the product consists of distinct but loosely aggregated primary particles. Such materials have potential for use as catalysts or catalyst supports.

Pore structure characterization of catalyst supports via low field NMR

Abstract: The pore structures of two types of catalyst support material were studied: {gamma}-alumina and silica aerogel. The alumina samples were commercial catalyst supports made in 1/8 inch diameter pellet form by Harshaw Chemical. Aerogels were prepared by forming a gel in a two-step, base-catalyzed process using TEOS, followed by supercritical drying to form the aerogel. Two different aerogels were made, one undergoing the drying process immediately after gel formation (non-aged), and the other being aged in the gel state for two weeks in a basic solution of 0.1 molar NH{sub 4}OH at 323 K before being supercritically dried (aged). The aging process is believed to alter the aerogel pore structure. The pore size distribution of the alumina material was determined via NMR and compared to results obtained by mercury intrusion and nitrogen adsorption/condensation techniques. The pore size distributions of the two aerogel samples were measured via NMR and nitrogen adsorption/condensation; the material was too compressible for porosimetry.

Wettability alteration of model sandstone surfaces by vapor-phase treatment with organosilanes

Abstract: The wettability of a rock-fluid system has a major influence on the amount of residual oil in a reservoir and its ease of recovery. We have investigated a technique for modifying the natural water-wetness of clean, dry mineral samples by chemically incorporating organosilanes onto their surfaces (silylation). The goal is to provide simulated core samples with different degrees of wettability. Data from wettability measurements on these model cores could then be compared to that obtained on actual reservoir core samples. Discussion will specifically focus on: (1) comparison of quartz plates silylated by our vapor-phase technique vs. a solvent-phase treatment; (2) relative performance of two different types of organosilanes; and (3) effect of temperature.

Temperature-programmed desorption study of CO on Pt reforming catalysts

Abstract: L'influence de la teneur en platine, de la taille des particules, de la dispersion, du chargement, de l'activite, des traitements de calcination, reduction et presechage sur les catalyseurs de platine deposes sur alumine est analysee au cours de la desorption programmee en temperature du monoxyde de carbone. Ces catalyseurs sont analyses au cours des operations de reformage

The use of laminar jet in determining the overall rate of liquid-liquid reactions

Abstract: Liquid-liquid reactions are encountered extensively in various chemical industries. As a typical example, sulfonation of aromatic hydrocarbons by concentrated sulfyric acid solutions may be mentioned. It has been demonstrated that in these reactions, diffusional resistances are important only at higher sulfuric acid concentrations, but that the overall rate can be correlated by a simple kinetic model at lower acid concentrations. Laminar jets are found to be suitable equipment by which liquid-liquid reactions can be effectively investigated. The present study on toluene and benzene sulfonation may be regarded as a typical example in this case. The major advantages of such equipment are, possibility of precise measurement of interfacial area and diffusivities, convenience in operation and control, and simplicity of handling the experimental data.

Diesel injectors additives for a clean exhaust

Abstract: Un essai moteur a ete developpe pour tester l'influence de differents detergents sur la proprete de l'injecteur, la production de fumee noire et la consommation de carburant diesel

Identification of dinuclear aromatics in the gas oil fraction of Kuwait petroleum

Abstract: For several decades removal of aromatics from crude oil fractions (e.g. kerosene and lubricating oils) has been practiced in oil refining to produce fuels and lubricants of lower aromatic content and hence of improved quality. These aromatics are suitable raw materials for the manufacture of aromatic solvents, aromatic process oils, high octane gasoline, and as basic materials for making detergents, perfumes and dyes. Detailed study of molecular structure and substituent effects on the retention characteristics of aromatic hydrocarbons have been reported on alumina, silica and various chemically bonded silicas containing -C/sub 18/, -NH/sub 2/, -R(NH)/sub 2//sub 2/, -CN, RCN, RON and phenyl-mercuric acetate for the compound class (ring-numbered) high performance liquid chromatography (2, 3, 8, 12, 24, 28). Previous work in this laboratory has demonstrated that individual normal and branched aliphatic hydrocarbons from kerosene and light gas oil were isolated and identified. This paper describes the extension of this work to cover the separation and identification of aromatic ring classes (mono-, di-, and tri-aromatics) in the gas oil fraction of Kuwait petroleum. Characterization and identification of the major components in the dinuclear aromatics is our primary objective in this study.

Catalyst characterization by infrared spectroscopic methods

Abstract: Infrared spectroscopy has been widely used for characterization of surfaces for over thirty years. Review, books and many articles attest to its continued popularity. Improvements in spectrometers and computer treatment of spectral data have increased interest in wider use of infrared for routine analytical characterization of catalysts. Infrared can give the same information on bulk composition or major surface compounds of solid catalysts as that obtainable on other solids. It is also a gentle, non-destructive technique for surface characterization, occasionally under reaction conditions. Surface studies of oxide-supported catalysts are usually limited to the region above 1000 cm{sup {minus}1}, however. Raman spectroscopy can provide additional information in favorable cases. Diffuse-reflectance, emission, photoacoustic, and other related spectroscopic methods also offer potential advantages, particularly in ease of sample preparation, but transmission methods are preferred when they can be used and quantitative comparisons are sought.

Synthesis of high surface area chromium(III) oxides

Abstract: Chromium(III) oxides can be prepared by a number of routes. They are catalysts for olefin hydrogenation or isomerization, the synthesis of halogenated hydrocarbons, isotopic exchange between alkanes and deuterium, and the dehydration of alcohols. Commercial sources of chromia often have relatively low surface areas (ca. 10 m{sup 2}/g). Different preparation routes result in chromium oxides with different surface characteristics, and previous synthetic efforts focused on generating the oxide with as high a surface area as possible. During the course of their work with aerogels, it occurred to them that the process of hypercritical venting should produce a much higher surface area product than the traditional xerogel-based routes reported earlier for chromium(III) oxide. With the application of the aerogel technology to the traditional synthetic routes, they obtained chromium oxides with surface areas (528-784 m{sup 2}/g) at least twice as large as previous (xerogel based) reports and pore volumes in excess of 3 cm{sup 3}/g.

Studies of hydrous sodium titanate ion-exchange materials for use as catalyst supports

Abstract: Understanding how the activity of a catalyst is related to the concentration and dispersion of active metals on the catalyst support is critical to designing materials having the optimum catalytic properties. We have developed synthetic techniques for controlling both the concentration and dispersion of nickel on hydrous sodium titanate catalyst supports. The techniques require an understanding of the solution chemistry of both the support material and dissolved metal species (hydrolysis products). In this paper, we present the results of a study of three nickel-loaded samples of hydrous sodium titanate in which the scale of the nickel dispersion ranges from the atomic level to the scale of large (50 nm) clusters. The catalysts are characterized by transmission electron microscopy (TEM), hydrogen chemisorption, and BET surface area measurements. In addition, the activity and selectivity of the Ni catalysts for the n-butane hydrogenolysis reaction is used to monitor the surface structures of Ni in the catalysts. 8 refs., 7 figs., 1 tab.