Characteristics of Coke Deposition Over a SAPO-34 Catalyst in the Methanol-to-Olefins Reaction

The deactivation of SAPO-34 catalyst in the methanol-to-olefins process has been studied at temperatures of 400 to 475°C. The catalyst activity keeps stable before a rapid deactivation occurs at a critical coke content. The analysis of retained coke species showed that methylbenzenes were the most abundant species at lower temperatures (400°C and 425°C), while polycyclic aromatics became the dominant species at 475°C. The growth in the retained coke species with increasing temperature comes from the enhanced reactivity of methylbenzenes and methylnaphthalenes at high reaction temperature, where methylnaphthalenes may function as another active reaction centers.     

Modeling of Coke Formation and Catalyst Deactivation in Propane Dehydrogenation Over a Commercial Pt-Sn/γ-Al2O3 Catalyst

Propane dehydrogenation was carried over a commercial Pt-Sn/γ-Al₂O₃ catalyst at atmospheric pressure and reaction temperatures of 580, 600, and 620°C and WHSV of 11 h^?1 in an experimental tubular quartz reactor. Propane conversions were measured for catalyst time on stream of up to nine days. The amounts of coke deposited on the catalyst were measured after one, three, six, and nine days on stream using a thermogravimetric differential thermal analyzer (TG-DTA) for each reaction temperature. The coke formation kinetics was successfully described by a coke formation model based on a monolayer-multilayer mechanism. In addition, catalyst deactivation was presented by a time-dependant deactivation function. The kinetic order for monolayer coke formation was found to be two, which would support a coke formation step involving two active sites. The kinetic order for multilayer coke formation was found to be zero. The activation energy for monolayer coke formation was found to be 29.1 kJ/mol, which was lower than the activation energy of about 265.1 kJ/mol for multilayer coke formation indicating that the presence of metals can promote coke formation on the catalyst surface.     

A kinetic model for delayed coking process of Iranian vacuum residues

A four-lump kinetic model was developed for delayed coking process of Iranian vacuum residues. The feedstock and products were considered as a unique and three separated lumps, respectively, in the model. The product lumps were included gas (C₁–C₄), distillate (C₅₊ –500?°C), and coke (toluene insoluble and 500?°C+). The reactions performed in an atmospheric batch pilot plant reactor by selected feeds at three temperatures (420, 450, and 480?°C) and four residence times (10, 30, 50, and 120?min). Reactions were assumed in first order and based on Arrhenius reaction rates. Also, the kinetic model was validated by a similar feed at different conditions that showed suitable precision with experimental results.     

A Physicochemical Evaluation of Modified HZSM-5 Catalyst Utilized for Production of Dimethyl Ether From Methanol

A number of HZSM-5 catalysts modified with 5 wt% Mg, Na, Zr, and Al as well as others modified with 5–60 wt% Zn prepared by wet impregnation. These materials were characterized by the NH₃-TPD, XRF, and XRD analyses and tested in a slurry reactor to determine their activities in dehydration of methanol solution in kerosene. Reactions were carried out at 230°C and 19 bar for 4 h of residence time in the reactor. Results showed that in the first series, the catalyst modified with Zr and in the second series, the one modified with 10 wt% Zn led to the highest methanol conversion. It was deduced that elimination of strong acid sites and partial replacement of active cations in the HZSM-5 zeolite lattice enhanced the performance and improved resistance against formation of hydrocarbons and other by-products such as olefins all of which acted as coke precursors. In order to determine the activation energy, the rate equation of Bercic and Levec was utilized and assumptions consistent with reaction conditions considered. Hence, rate constants determined empirically through fitting experimental data to the aforementioned rate equation. Ultimately, the related activation energies were calculated. In comparison with common dehydration catalysts such as alumina, the activation energies of the modified catalyst decreased. Nonetheless, the superior performance of the modified HZSM-5 attributed mainly to the elimination of strong surface acid sites by partial substitution of cations resulted in prevention of coke and undesired hydrocarbon formation.     

Cyclohexane Dehydrogenation Using an Economical Iron Catalyst: Influence of Alumino-Silicate Structure on the Catalytic Activity

Abstract

The effect of mixing both local Egyptian hematitic ore and activated aluminosilicate material (bentonite clay) on the dehydrogenation activity of the former was studied.

Three mixtures were prepared in which bentonite percentages were 10, 20, and 40 wt%. Cyclohexane used as a model reactant for the catalytic dehydrogenation reaction carried out in catalytic flow system within reaction temperature ranged from 150 to 500°C in the presence of hydrogen stream (75 mL/min) and at constant space velocity 3.71 h^?1.

The results obtained indicated that in spite of the drop in the selectivity of the local material toward benzene formation by clay addition, a distinct increase in the benzene yield was observed. The maximum conversion attained ～28.14% at reaction temperature 500°C using a mixture containing 20 wt% activated bentonite.     

Wild melon: a novel non-edible feedstock for bioenergy

In the present research work, a non-edible oil source Cucumis melo var. agrestis(wild melon) was systematically identified and studied for biodiesel production and its characterization. The extracted oil was 29.1% of total dry seed weight. The free fatty acid value of the oil was found to be 0.64%, and the single-step alkaline transesterification method was used for conversion of fatty acids into their respective methyl esters. The maximum conversion efficiency of fatty acids was obtained at 0.4 wt% Na OH(used as catalyst), 30%(methanol to oil, v/v) methanol amount, 60 ℃ reaction temperature,600-rpm agitation rate and 60-min reaction time. Under these optimal conditions, the conversion efficiency of fatty acid was 92%. However, in the case of KOH as catalyst, the highest conversion(85%) of fatty acids was obtained at 40%methanol to oil ratio, 1.28 wt% KOH, 60 ℃ reaction temperature, 600-rpm agitation rate and 45 min of reaction time.Qualitatively, biodiesel was characterized through Fourier transform infrared spectroscopy(FTIR) and gas chromatography and mass spectroscopy(GC–MS). FTIR results demonstrated a strong peak at 1742 cm~(-1), showing carbonyl groups(C=O)of methyl esters. However, GC–MS results showed the presence of twelve methyl esters comprised of lauric acid, myristic acid, palmitic acid, non-decanoic acid, hexadecanoic acid, octadecadienoic acid and octadecynoic acid. The fuel properties were found to fall within the range recommended by the international biodiesel standard, i.e., American Society of Testing Materials(ASTM): flash point of 91 ℃, density of 0.873 kg/L, viscosity of 5.35 c St, pour point of-13 ℃, cloud point of-10 ℃, total acid number of 0.242 mg KOH/g and sulfur content of 0.0043 wt%. The present work concluded the potential of wild melon seed oil as excellent non-edible source of bioenergy.     

Catalytic co-cracking of waste polypropylene and residual fuel oil

Abstract

Industrial waste polypropylene (PP) homopolymer and residual fuel oil (RFO) were pyrolyzed together in presence of catalyst ZSM-5 under the atmospheric pressure with different mixing ratios of the feedstocks. The experiments were carried out in a batch reactor at two different temperatures of 500?°C and 600?°C with the blended mixture (PP/RFO) to catalyst (ZSM-5) ratio of 4:1. The effects of blending ratios between the two feedstocks and temperature with respect to the yield of the products oil, gas, and residual coke were determined. The optimum blending ratio of PP and RFO with respect the higher quantity yield of liquid product was found to be 1:1 at 500?°C. The percentages of liquid fuel, gas, and coke were observed to be 74.8%, 10.2%, and 15% at 500?°C.     

COKE CHARACTERISTICS IN RELATION TO THE COLLOIDAL. MATTER OF PETROLEUM FOR THERMAL. PROCESSES

Abstract

The purpose of this work is to research the characteristics of the production of coke in thermal and hydrothermal cracking from residual oils and their deasphalted oils Using ethyl acetate, because it allows the elimination of both resins and asphaltenes (colloidal matter) from the parent oil in only one step. This improves the deasphalted oil as coke precursors and basic nitrogen compounds present in the resin fraction are practically eliminated.

A 104 ml batch autoclave reactor with a cooling system was used for the thermal and hydrothermal cracking experiments. This reactor can withstand temperatures of up to 500^°C, pressures of 500 bar and a rocking velocity of 1 Hz. The influence of the temperature was investigated at 400, 425 and 450^°C and at 0, 20, 40, 80,     

Effect of Severity on Hydrotreating of Demetallized Oil Monitored by 1H-NMR Spectroscopy

Abstract

A study on aromatic hydrogenation of demetallized oil has been carried out using a commercial catalyst under pilot plant reaction conditions similar to those found in industrial processes. The feedstock was contacted with the catalysts in a trickled bed reactor unit at 330°C, 350°C, and 370°C. A combination of physicochemical characterization of feed and products and ¹H-NMR spectra was used to monitor changes in the aromatic fractions caused by variation in reaction temperature. Analysis of the ¹H-NMR spectra, along with the quantitative variation in the areas of the resonance lines, showed that the diaromatics with relatively long alkyl changes present in the lightest distillation cuts of the products were highly hydrogenated. In contrast, smaller changes in aromaticity in the heaviest fractions were observed under the same conditions. A limit of about 2 wt% of the integrals corresponding to the diaromatic+ species suggests a thermodynamical limitation of hydrogenation under the studied reaction conditions.     

Simulation analysis of steam gasification of petroleum coke with CaO

Abstract

The work deals with the effect of calcium oxide adsorption on the production of hydrogen and methane in steam gasification of petroleum coke using Aspen Plus process simulator. The prediction accuracy of the proposed model is verified by comparing with the existing experimental results. The effects of water vapor flux, the mass ratio of calcium oxide to petroleum coke, pressure, temperature on hydrogen or methane gasification from petroleum coke steam are studied. The production of hydrogen from petroleum coke gasification requires a low temperature and low pressure environment, while increasing the flow of water vapor is beneficial to the production of hydrogen. Maximum H₂ volume fraction of 87.3% is obtained at a temperature of 600?°C, a pressure of 0.1?MPa, the mass of steam to petroleum coke is 1, and the mass of CaO to petroleum coke is 3. The H₂ and CO₂ volume fractions are found to be increased and decreased by 20% and 27.8% respectively, when compared with the corresponding non-CaO case. The production of methane from petroleum coke gasification requires a low temperature and high pressure environment, while decreasing the flow of water vapor is beneficial to the production of methane. Maximum CH₄ volume fraction of 63% is obtained at a temperature of 600?°C, a pressure of 1?MPa, the mass of steam to petroleum coke is 1, and the mass of CaO to petroleum coke is 1. The CH₄ and CO₂ volume fractions are found to be increased and decreased by 14.4% and 21% respectively, when compared with the corresponding non-CaO case.     

Cracking of Maya Crude Asphaltenes

Cracking of Maya crude asphaltenes was carried out in a batch reactor at the following reaction conditions: temperature of 380–410°C, total pressure of 2 MPa, and asphaltenes/catalyst ratio of 5 g/g using NiMo commercial catalyst. n-hexadecane was used to keep asphaltenes dispersed and reaction time ranged from 0 to 60 min. The products were lumped into four fractions: asphaltenes, maltenes, gases, and coke. A kinetic model assuming pseudo–first-order parallel reactions was used to fit the experimental data.     

Specifics of the deactivation of acid and zinc-containing propane aromatization catalysts

The specifics of the deactivation of acid and Zn-containing MFI catalysts in the propane aromatization reaction at high-feed space velocities (600–2400 h^?1) and temperatures (550–610°C) was studied. The kinetics of the buildup of carbonaceous products (coke) was investigated in situ during the catalytic reaction in a thermal analyzer coupled to a mass spectrometer and a gas chromatograph (TA-MS-GC). The nature of the coke was studied by means of differential thermal analysis (DTA) and elemental analysis. It was found that the buildup of heavy coke on the H-MFI zeolite takes place on the outer crystal surface and pore openings, thus leading to a decrease in the propane conversion at the beginning of the reaction. In contrast, light coke appears first and is transformed to heavy coke at later stages on Zn/H-MFI. The light coke leads to a decrease in the yield of methane, ethane, and ethylene, and the heavy coke impedes the formation of aromatic hydrocarbons.     

Kinetics and Selectivity of Asphaltene Thermal Cracking,Thermal Hydrocracking,and Catalytic Hydrocracking

Abstract

A pentane-insoluble asphaltene was processed by thermal cracking, thermal hydrocracking, and catalytic hydrocracking in a microbatch reactor at 430°C. The experimental data of asphaltene conversion fit second-order kinetics adequately to give the apparent rate constants of 1.704 × 10^?2, 2.435 × 10^?2, and 9.360 × 10^?2 wt frac^?1 min^?1 for the above three cracking processes, respectively. A three-lump kinetic model is proposed and solved to obtain rate constants of parallel reactions of asphaltenes to produce liquid oil (k₁) and gas + coke (k₃) and a consecutive reaction from liquid to gas + coke (k₂). The value of k₁ is 1.697 × 10^?2, 2.430 × 10^?2, and 9.355 × 10^?2 wt frac^?1 min^?1; k₂ is 3.605 × 10^?2, 2.426 × 10^?2, and 6.347 × 10^?3 min^?1; and k₃ is 6.934 × 10^?5, 5.416 × 10^?5, and 4.803 × 10^?5 wt frac^?1 min^?1 for asphaltenes thermal cracking, thermal hydrocracking, and catalytic hydrocracking, respectively. Analysis of selectivity shows that the catalytic hydrocracking process provides the highest liquid production, and the coking process provides the highest coke formation, as expected. An induction period of coke formation was found to increase from thermal cracking to thermal hydrocracking to catalytic hydrocracking process.     

Effect of Organophosphorous Compounds as Coke Inhibitors on Coking Rate in the Pyrolysis of Naphtha

Abstract

The reduction in the rate of coke formation during naphtha pyrolysis due to the injection of triphenyl phosphine (TPP), tri-o-tolyl phosphine (TTP), and triphenyl phosphine oxide (TPPO) has been investigated in a jet stirred reactor at atmospheric pressure in the temperature range of 800–900°C. Coke formation was significantly reduced in the presence of the additives. The data are consistent with the formation of a metal–phosphorous complex that passivates the metal activity for coke formation. Scanning electron microscope (SEM) and energy dispersive X-ray (EDX) techniques were used for morphological and elemental surface analyses respectively. It was found, that coke formed in presence of organophosphorous inhibitors are softer and have less metal concentrations.     

Influence of coker-derived liquids on coking performance of Venezuelan heavy oil residue

Coking technological improvements are required to effectively upgrade/refine extra-heavy oil residues. The influence of types and blending ratios of coker-derived liquids on the coking performance of Venezuelan residue was studied in terms of product distribution and coke morphology. Blending of the coker diesel distillates (200–350?°C) with the residues was not suggested, given the negative interactions at all blending ratios (0–0.6) as concluded from coke yield analysis. Blending of the coker gas oil improved the coke quality and inhibited the coke formation. The recycle of heavy coker gas oil (430?°C+) at a blending ratio of 0.3 was most favorable.     

Production of biodiesel from unused algal biomass in Punjab, India

Biodiesel from inedible sources has become prominent in last few decades. But it is economically incompatible with petroleum diesel. At the same time, both petro-diesel and biodiesels are concerned with environmental pollution, global warming, etc. Algae, on the other hand, utilize CO2 for their growth and can minimize some sort of pollution level and results in carbon credit for a country. In Punjab, India, algae are seen to grow in many water bodies. But all those are taken away and dumped in vats. Some of this huge biomass was used for production of biodiesel in this work. Extraction of oil from algae was conducted by using Soxtherm(solvent extraction). An amount of 9 wt% of algal oil was extracted by comparatively costly hexane, whereas 8% extraction was done by cheaper acetone. In the transesterification reaction, molar ratio(methanol: oil) of 6:1, catalyst(KOH) concentration of 3 wt%, reaction temperature of 60 °C, 60 min reaction time and a settling time of 2.5 h were found to be optimum conditions to get maximum ester with minimum free fatty acid content and viscosity. A statistical analysis for the transesterification procedure also showed a methanol-to-oil molar ratio of 6:1 and catalyst concentration of 3 wt% to be the optimum. Characterization of biodiesel was done and compared with ASTM/BIS standards. Most important properties of biodiesel ester like viscosity(3.12 c St or 3.12 mm2/s), cloud and pour point(-1 and-6 °C, respectively), flash and fire point(153 and 158 °C), carbon residue content(0.03%), acid number(0.36 mg of KOH/gm) were within the range of concerned standards.     

Dehydrogenation of propane in a combined membrane reactor with hydrogen-permeable palladium module

The basic features of the propane dehydrogenation reaction in a combined membrane reactor with a hydrogen-permeable palladium module and chromia-alumina catalyst (9.0 wt % Cr) in the temperature range of 520–580°C have been studied. Under optimum conditions (T, 550°C; propane space velocity and a stripping gas flow rate of 600–900 h^?1 and 100–250 cm³/min, respectively), the feedstock conversion to propylene increases by a factor of 1.6–2.0. It has been suggested that compliance between the rate of H² formation and its withdrawal through the membrane is of considerable importance.     

Editorial: Emerging Technologies for Petroleum Waste Management

ABSTRACT

An estimate of the quantity of toxic coke deposited on fresh and regenerated Pt/Alj₂O₃ catalyst has been determined for methylcyclopentane (MCP) reforming in a Berty CSTR at 390°C, W/F=0·11 g min cm^-3, total pressure of 1 atm and MCP partial pressure of 9·2 × 10^-2 atm in H₂ or N₂ carrier. Eleven cycles consisting each of catalyst deactivation, regeneration and reduction were investigated with 3 in H₂ and 8 in N₂. Oxidizable (primary) coke deposits were higher in N₂. However, higher levels of toxic (secondary) coke were deposited in H₂. The ratio of oxidizable to toxic coke lies between 1?15×10³ in H₂ and 22 ? 55 × 10³ in N₂ The coke-time profiles for secondary coke removal exhibited maxima suggestive of three types of secondary coke with varying reactivity in H₂. Furthermore, the results strongly suggest that the cokes were layered on acidic coke forming sites with the solid phase transformation of primary to secondary coke occurring at the catalyst-coke interface.     

Effect of heating rate and additives (MgO and Al2O3) on a diesel like-fuel issued from waste engine oil pyrolysis

Pyrolysis experiments were conducted at atmospheric pressure in a batch reactor ranging from room temperature until 420?°C. The suitable heating rate was studied by keeping constant the reaction temperature at several levels (300, 320, 340, 360, 380 and 400?°C) for 60?min. by application the best heating program; MgO and Al₂O₃ additives are examined at various proportions (1, 2, 3, 4 and 5% by weight). It has been shown that the addition of MgO (1-2% by wt.) leads to a supplemental improvements in the DLF quality where the properties are the closet to those of conventional diesel fuel.     

Castor oil biodiesel production and optimization

Biodiesel is evolving to be one of the most employed biofuels for partial replacement of petroleum based diesel fuel, especially in recent years. The most widely used feedstocks for biodiesel production are vegetable oils. In this work, biodiesel production from castor oil has been synthesized by homogenous alkaline transesterification. The influence of catalyst concentration, methanol:oil molar ratio, reaction temperature and reaction time in the methyl ester content reached by castor oil transesterification have been evaluated. A yield of 95?wt% biodiesel was achieved at 1?wt% KOH, 60?°C, 9:1 methanol:oil ratio and 30?min reaction time. Transesterification at temperature 30?°C gave a yield compatibles with that obtained at 60?°C. The composition of the fatty acid methyl ester was determined by Gas Chromatography. The castor oil biodiesel produced was blended with different concentrations of petrodiesel to obtain B5, B10 and B20. The biodiesel properties and its blends were determined according to the standard test methods of analysis. The results showed that Castor oil biodiesel in the blends could lower the cloud point value, but simultaneously, increases the viscosity of the diesel–biodiesel blends. Thus, castor oil biodiesel with its very low cloud and pour points is suitable for using in extreme winter temperatures.