Catalytic Naphtha Reforming Research Articles

Effect of Oxidized Tin Interfacial Atoms on Methylcyclohexane Dehydrogenation Catalyzed by γ‐Alumina Supported Platinum Clusters

AbstractTin (Sn) doped platinum (Pt) nanoparticles supported on γ‐alumina are important materials catalyzing various reactions, such as the dehydrogenation of methylcyclohexane (MCH) into toluene, involved in liquid organic hydrogen carriers process, and naphtha catalytic reforming. The role of oxidized forms of Sn, remains misunderstood. Relying on catalysts' models made of a Pt13cluster on the (100) surface of γ‐alumina, the location and effects of Sn4+and Sn2+ interfacial atoms are investigated by density functional theory (DFT) calculations. A simulated annealing approach based on ab initio molecular dynamics enables to explore the configurations of the catalytic systems. The Pt clusters' stabilities and that of the adsorbed molecular intermediates are linked to the electronic properties of the cluster and to its ductility modulated by the adsorbed species, the alumina support and the Sn atoms. The Gibbs free energy profiles related to the reaction mechanism of the MCH dehydrogenation into toluene are quantified on the basis of transition state search. The energy span concept reveals that the dual (either detrimental or beneficial) impact of Sn oxidized forms on the intrinsic reactivity of the Pt13 cluster depends on temperature. Based on this DFT analysis, we attempt to clarify the debated role of Sn oxidized species.

Synthesis and Determination of Active Acidic/Basic Sites on Zn Loaded Zeolite (ZSM-5) Catalyst & Its Role in Catalytic Reforming of Naphtha Using HPMR Reactor

Synthesis and Determination of Active Acidic/Basic Sites on Zn Loaded Zeolite (ZSM-5) Catalyst & Its Role in Catalytic Reforming of Naphtha Using HPMR Reactor

Conventional Synthesis of Zinc Loaded Extruded ZSM-5 Its Surface Analysis by TPD Technique and Application in Catalytic Reforming of Naphtha Using HPMR Reactor

Conventional Synthesis of Zinc Loaded Extruded ZSM-5 Its Surface Analysis by TPD Technique and Application in Catalytic Reforming of Naphtha Using HPMR Reactor

Modeling and Parameter Tuning for Continuous Catalytic Reforming of Naphtha in an Industrial Reactor System

A two-dimensional mathematical model was developed to simulate naphtha reforming in a series of three industrial continuous catalytic regeneration (CCR) reactors. Discretization of the resulting partial differential equations (PDEs) in the vertical direction and a coordinate transformation in the radial direction were performed to make the model solvable using Aspen Custom Modeler. A sensitivity-based parameter subset selection method was employed to identify the most influential parameters within the model. Tuning of 8 out of 180 parameters was used to ensure that model predictions match experimental data from one steady-state run. The updated parameter values improved the model fit to the data, reducing the weighted least-squares objective function for parameter estimation by 73%. The proposed model was used to predict reactor temperatures, catalyst coke weight fraction at the exit of the third reactor, and benzene flowrate from the outlet of the third reactor. The simulation results demonstrated a good agreement between the simulated values and the industrial measurements. Finally, the reactor model was utilized to explore the effects of changes in inlet temperatures and inlet level of catalyst deactivation, providing valuable insights for identifying desirable operational conditions that will improve the overall efficiency of the CCR process.

Design of New Composites Nano-Catalysts for Naphtha Reforming Process: Experiments and Process Modeling

The naphtha catalytic reforming process is evaluated by designing new composite nano-catalysts. Three catalysts were prepared for this process. The first catalyst was molybdenum carbide composite with platinum over HY zeolite (Mo2C.Pt/HY zeolite), the second catalyst was molybdenum carbide composite with platinum over modified zeolite by cerium nitrate (Mo2C.Pt/CeY zeolite), and the last catalyst was bimetallic titanium and platinum with a titanium content of 1% and platinum content of 0.11% over HY zeolite (Pt.Ti/HY zeolite). All catalysts were tested with several tests, mainly X-Ray Diffraction (XRD), BET surface area, and pore volume. All these substances were applied as catalysts for the reforming process of Iraqi heavy naphtha at the following operating conditions: reaction temperature (480, 500, and 520 ), reaction pressure (10, 12.5, and 15 bar), liquid hourly space velocity (LHSV) at 2 hr-1, and constant hydrogen to hydrocarbon ratio (H2/ HC) of 4. All the reforming reactions occurred in a packed bed pilot plant reactor to investigate its stability and activity during the reforming process. All the developed catalyst samples showed sensational stability even at operating under difficult circumstances. The best catalyst was Pt.Ti/HY zeolite based on the results obtained with respect to the octane number (86.2) at 520 and 15 bar. Also, a mathematical model to describe the reforming process with high accuracy was built and simulated using gPROMS software. The results were very satisfying since the most significant error with the wt% of reformate was 4.9% (the experimental aromatics content was 23.94 wt.%, while the predicted result was 21.67 wt.%), while Research Octane Number (RON) error was 4.7% (the experimental RON was 81, whereas the predicted value of RON was 85) among all the results meaning that the simulating was valid to describe the process.

Integral techno-economic comparison and greenhouse gas balances of different production routes of aromatics from biomass with CO2 capture

The techno-economic performance and CO2 equivalent (CO2eq) reduction potential of bio-based aromatic production cases with and without CO2 capture and storage (CCS) have been evaluated and compared to those of fossil-based aromatic production. The bio-cases include tail gas reactive pyrolysis (TGRP), catalytic pyrolysis (CP), hydrothermal liquefaction (HTL), gasification-methanol-aromatics (GMA), and Diels-Alder of furan/furfural combined with catalytic pyrolysis of lignin (FFCA). The crude oil-based naphtha catalytic reforming (NACR) routes have GHG emissions of 43.4 and 43.9 t CO2eq/t aromatics with and without CCS (NACR-CCS), respectively. Except for HTL, all the biomass cases with CCS show negative emissions between −6.1 and −1.1 t CO2eq/t aromatics with avoidance costs ranging from 27.7 to 93.3 $/t CO2eq. Under favorable conditions, GMA with CCS (GMA-CCS) has the lowest emissions (−14.6 t CO2eq/t aromatics), while CP with CCS (CP-CCS) shows the lowest avoidance cost (12.3 $/t CO2eq). All biomass based aromatics production techniques are currently at the laboratory or demonstration stages, except for CP, which has pilot plants. The results indicate that bio-based aromatics production, with their reasonable avoidance costs and low, or potentially negative, greenhouse gas (GHG) emissions, are an attractive option to compensate for the expected aromatic production shortages in the coming decades.

Emergy evaluation of aromatics production from methanol and naphtha

Aromatics are traditionally produced by the catalytic reforming of naphtha. However, with the demand of aromatics increasing and the reserves of petroleum resources declining, measures should be made to reduce the dependence of aromatics production on petroleum resources. Methanol-to-aromatics is proved to be an effective way to replace traditional naphtha-to-aromatics path. In order to compare the economic and environmental performance of aromatics production from naphtha and methanol, this paper carries out an emergy evaluation for each system by sorting out the simulation and literature data. Based on the emergy data collected, the emergy indices of each system are calculated. The results show that the sustainabilities of methanol-to-aromatics systems are higher than that of the naphtha-to-aromatics system, indicating the advantages of aromatics production from methanol. Among the methanol-to-aromatics systems, the aromatics from biomass-methanol system has the highest sustainability, indicating that the biomass based methanol-to-aromatics system is worth promoting. The sustainability indexes of methanol-to-aromatics systems based on coal and coke oven gas are less than 1, which means unsustainable. Meanwhile, the sustainability of natural gas based system is slightly higher than 1. The economic and environmental benefits of these systems can be optimized by improving resource utilization and reducing investment costs. Furthermore, the combination of different raw materials for methanol production should be considered.

A Thermodynamic Analysis of Naphtha Catalytic Reforming Reactions to Produce High-Octane Gasoline

The catalytic naphtha reforming process is key to producing high-octane gasoline. Dozens of components are involved in this process in hundreds of individual catalytic reactions. Calculations of concentrations at equilibrium, using equilibrium constants, are commonly performed for a small number of simultaneous reactions. However, the Gibbs free energy minimization method is recommended for the solution of complex reaction systems. This work aims to analyze, from the point of view of thermodynamic equilibrium, the effect of temperature, pressure, and the H2/HC ratio on the reactions of the catalytic reformation process and evaluate their impact on the production of high-octane gasoline. Gibbs’s free energy minimization method was used to evaluate the molar concentrations at equilibrium. The results were compared with those obtained in the simulation of a catalytic reforming process to evaluate the optimal conditions under which the process should operate.

Molecular Kinetic Modeling of Catalytic Naphtha Reforming: A Review of Complexities and Solutions

ABSTRACT Kinetic modeling is receiving more attention in recent years due to the availability of advanced computational tools and enhancement in the accuracy of analytical techniques. These advances facilitate investigation of the chemical transformations on a molecular level rather than on the bulk properties, such as density, distillation cuts, or octane number. Molecular kinetic modeling of catalytic naphtha reforming is of particular interest as it processes light petroleum fraction that enable full molecular-level analysis. Moreover, the process is an important source of valuable chemicals, hydrogen, and high-octane transportation fuel. Over the years, the goal of the kinetic modeling has evolved from predicting the octane number or other properties of reformate to tracking a particular molecule, such as benzene. Several kinetic models are published in the last decade – each of them strived to adopt somewhat different approach either in the complexity of proposed reaction network or in the methodology of estimating the kinetic parameters. The approaches that have been considered in formulating the rate expressions include: (i) classical power-law model; (ii) models based on Langmuir-Hinshelwood–Hougen–Watson kinetics; (iii) structure-oriented kinetics approach; and (iv) single-event fundamental model. The review presents a systematic comparison of these kinetic models in depth as well as their limitations. An appraisal of the mathematical methods for estimation of kinetic parameters and the computational tools employed for determination of the numerical values of these parameters is made. Finally, the current trends and outlook of this field is presented.

Model-Based Quality, Exergy, and Economic Analysis of Fluidized Bed Membrane Reactors.

In petroleum refineries, naphtha reforming units produce reformate streams and as a by-product, hydrogen (H2). Naphtha reforming units traditionally deployed are designed as packed bed reactors (PBR). However, they are restrained by a high-pressure drop, diffusion limitations in the catalyst, and radial and axial gradients of temperature and concentration. A new design using the fluidized bed reactor (FBR) surpasses the issues of the PBR, whereby the incorporation of the membrane can improve the yield of products by selectively removing hydrogen from the reaction side. In this work, a sequential modular simulation (SMS) approach is adopted to simulate the hydrodynamics of a fluidized bed membrane reactor (FBMR) for catalytic reforming of naphtha in Aspen Plus. The reformer reactor is divided into five sections of plug flow reactors and a continuous stirrer tank reactor with the membrane module to simulate the overall FBMR. Similarly, a fluidized bed reactor (FBR), without membrane permeation phenomenon, is also modelled in the Aspen Plus environment for a comparative study with FBMR. In FBMR, the continuous elimination of permeated hydrogen enhanced the production of aromatics compound in the reformate stream. Moreover, the exergy and economic analyses were carried out for both FBR and FBMR.

Simulation and optimization of continuous catalytic reforming: Reducing energy cost and coke formation

Continuous catalytic naphtha reformers are one of the main refinery units producing hydrogen. Reliable and comprehensive modeling of such a complex and integrated refinery unit plays a pivotal role in optimization to increase the efficiency of the process. A reaction network with 26 pseudo components and 58 reactions, considering coke formation and catalyst activity, was proposed to predict the outlet compositions of reactors in more detail. The whole unit, including reaction and purification sections, was simulated to cover all products. NOMAD optimizer, with the mesh adaptive direct search algorithm, is used to minimize energy costs. Non-linear constraints were defined to guarantee the quality of the final products. The optimized decision variables reduced the energy cost by 13.5%, mainly caused by a significant decline in natural gas consumption. The simulation also indicated an increase of 4800 ton/y in reformate production, which the product is rich in aromatics. By contrast, LPG, hydrogen-rich gas, and coke production dropped by nearly 4355, 321, and 127 ton/y, respectively. The coke production decline can significantly increase the catalyst lifetime and decrease the operating cost of the catalyst regeneration unit.

Non-thermal plasma assisted catalytic reforming of naphtha and its model compounds with methane at near ambient conditions

Naphtha reforming processes are widely used for high-octane gasoline production. These processes require high reaction temperature and high pressure of expensive hydrogen. Also, olefins and aromatics are produced for achieving high octane number, which could cause severe environmental issues. Here, we report a novel method of non-thermal plasma assisted catalytic reforming of naphtha at near ambient conditions. Conventionally used hydrogen has been replaced by cheaper methane in this study. Non-thermal plasma could effectively convert methane and naphtha to high-quality fuel at near room temperature and atmospheric pressure. A high-quality fuel with high content of iso-paraffin and low content of olefin and aromatic is produced over optimized Ga/mix-ZSM-5 with non-thermal plasma applied. The produced liquid product has a notably higher iso-paraffin content (increased from 21.5%–40.5%) than raw naphtha while the coke deposition (17.4 %) and the content of olefins (decreased from 13.5%–7.8%) and aromatics (dropped from 18.1%–5.9%) are well controlled. The partial desulfurization of fed coker naphtha by close to 60 % is also successfully achieved. A systematic model compounds study is conducted to investigate the involved mechanism of non-thermal plasma assisted catalytic naphtha reforming and coke deposition. Based on the studies of C6-C16 model compounds (including paraffins, olefins, dienes, cyclo-paraffins, cyclo-olefins and aromatics), a hypothetic reaction mechanism is proposed. A series of control experiments is also carried out to reveal the synergistic effect between non-thermal plasma, catalyst, and methane participation. This research thus pioneers a cost-effective and environmental-friendly route for naphtha reforming at mild conditions.

Kinetic study and Modeling of heavy Naphtha Catalytic Reforming process in AL-Daura Refinery

In the present work, kinetics and modeling of heavy naphtha catalytic reforming process in Al-Daura refinery-Midland refineries Company were studied. A proposed reaction scheme involving (15 pseudo components) connected together by a network of 30 reactions for components in the C6-C8+ range have been modeled. In the present work, kinetics and modeling of heavy naphtha catalytic reforming process in AL-Daura refinery-Midland refineries Company were studied. A proposed reaction scheme involving (15 pseudo components) connected together by a network of 30 reactions for components in the C6-C8+ range have been modeled. The proposed model has been solved numerically using the 4th order Runge–Kutta approach. Alteration of components and temperature, with time and reactor length was evaluated. Results showed that the rate of formation of aromatics is becoming slower as the reactants proceed to the third reactor. The catalytic reaction rates in the reformer are well represented by the Hougen-Watson Langmur-Hinshelwood (HWLH) type form. The deactivation of catalyst causes the reactor behavior to continue changing over a longer period of time. This clearly seems to pay off in the scenario where coke deposition plays such a major role. It was also found that the rate of coke formation increases with the progress from first to the last bed, so keeping a decreasing inlet temperature profile from first to the last bed would lead to more uniform coke content in each bed. The production rate of reformate has a negative impact on the octane number. Temperature drop across the first reactor (~ 45oC) is larger than the temperature drops across the other two reactors (10-12oC). This could be related to the endothermic reaction rate which is faster in the first reactor. The results show that perfect agreement of temperatures, compositions, and fractions molar flow rate at the exit of the third reactor is obtained between predicted values and industrial values.This confirmed the reliability of the present model.

Study on direct conversion of Naomaohu coal pyrolysis heavy oil to aromatics

The pyrolysis tar from Naomaohu coal was separated by distillation apparatus. Four components of heavy oil above 320°C were analyzed. The result showed the colloid content was 28.84% and the asphaltene content was 35.12%, and both were difficult to convert in hydrogenation. 13C-NMR results showed that the relative molar ratio of aromatic carbon in heavy oil was 71.16%, which indicated that aromatic compounds in heavy fraction were dominant. The heavy fraction was treated by suspension bed and fixed bed cracking. The asphaltene and colloid were almost completely converted. The yield of naphtha with boiling point below 180°C was 66.95%, and the diesel with boiling point higher than 180°C was 17.84%. Oxygen, nitrogen and sulfur contained in heteroatoms were almost completely removed. Catalytic reforming of naphtha was carried out. The results showed that the number of cycloalkanes decreased by 60.23%, and the number of aromatics increased by 65.8%, which indicated that the dehydrogenation and aromatization of cycloalkanes occurred mainly. While the number of n-alkanes decreased by 13.42%, which indicated that the isomerization and cyclization of n-alkanes occurred simultaneously. The catalytic reforming oil contained more benzene, toluene, xylene and ethylbenzene, and the contents were 11.97%, 23.15%, 21.43% and 3.48% respectively. In the direct conversion process of heavy oil from coal pyrolysis, the transmissibility of basic structural units of coal was significantly reflected.

Mathematical modeling and optimization of semi-regenerative catalytic reforming of naphtha

Catalytic naphtha reforming is extensively applied in petroleum refineries and petrochemical industries to convert low-octane naphtha into high-octane gasoline. Besides, this process is an important source of hydrogen and aromatics obtained as side products. The bifunctional Pt-catalysts for reforming are deactivated by coke formation during an industrial operation. This results to a reduction in the yield and octane number. In this paper modeling and optimization of a semi-egenerative catalytic reforming of naphtha is carried out considering catalyst deactivation and a complex multicomponent composition of a hydrocarbon mixture. The mathematical model of semi-egenerative catalytic reforming considering coke formation process was proposed. The operating parameters (yield, octane number, activity) for different catalysts were predicted and optimized. It was found that a decrease in the pressure range from 1.5 to 1.2 MPa at the temperature 478–481 °C and feedstock space velocity equal to 1.4–1 h induces an increase in the yield for 1–2 wt.% due to an increase in the aromatization reactions rate and a decrease in the hydrocracking reactions rate depending on the feedstock composition and catalyst type. It is shown that the decrease in pressure is limited by the requirements for the catalyst stability due to the increase in the coke formation rate. The criterion of optimality is the yield, expressed in octanes per tons.

Mechanistic modeling and numerical simulation of axial flow catalytic reactor for naphtha reforming unit.

Naphtha catalytic reforming (NCR) process has been of tremendous attention all over the world owing to the significant requirement for high-quality gasoline. Industrialized naphtha reforming unit at oil refineries applies a series of fixed bed reactors (FBRs) to improve the quality of the low-octane hydrocarbons and convert them to more valuable products. The prominent purpose of this research is to understand the catalytic reactor of naphtha reforming unit. For this aim, an appropriate mechanistic modeling and its related CFD-based computational simulation is presented to predict the behavior of the system when the reactors are of the axial flow type. Also, the triangular meshing technique (TMT) is performed in this paper due to its brilliant ability to analyze the results of model’s predictions along with improving the computational accuracy. Additionally, mesh independence analysis is done to find the optimum number of meshes needed for reaching the results convergence. Moreover, suitable kinetic and thermodynamic equations are derived based on Smith model to describe the NCR process. The results proved that the proceeding of NCR process inside the reactor significantly increased the concentration amount of aromatic materials, lighter ends and hydrogen, while deteriorated the concentration amount of naphthene and paraffin. Moreover, the pressure drop along the reactor length was achieved very low, which can be considered as one of the momentous advantages of NCR process.

Metal carbide as a potential non noble metal catalyst for naphtha reforming

In petroleum refining, continuous catalytic reforming of heavy naphtha is an important process to produce high value products such as hydrogen and aromatics from the low-value feedstock. Pt-Sn supported on chlorinated alumina is an accepted catalyst over last seven decades. However, use of expensive noble metals and corrosion due to halogen leaching are major issues associated with this catalyst. Such problems can be addressed by replacing the precious Pt metal with equally active and a stable non-precious metal catalytic material over suitable non-chlorinated solid acidic supports. In the present study Fe5C2, WC, Fe2W2C, Mo2C carbide materials have been explored as alternatives to Pt and these materials have been synthesized by solid-state temperature-programmed reaction and supported on different zeolites for imparting acidic function to the catalyst. Screening of these catalyst combinations for heavy naphtha reforming under suitable reaction conditions shows that, Mo2C supported on HY zeolite is found to be an active catalyst compared to any other carbide and zeolite combinations, with product aromatics in the range of 50 wt%, RON of 96, while maintaining reformate yields around 91 wt%.

Effect of hydrogen partial pressure on catalytic reforming process of naphtha

The semi catalyst regenerative commercial naphtha catalytic reforming of Kaduna Refinery, Nigeria is modelled and simulated with general process modelling systems (gPROMS) model builder 5.0.0 which is a computational tool in modelling process and complex chemical engineering processes. The thermodynamic and kinetics parameters used are obtained from the referenced literature. The model was validated with data from literature and was used to simulate the commercial data of KRPC. Simulation results obtained were good compared with the plant and literature data and these results were used in monitoring the plant performance and the temperature and concentration profiles of the parafins, naphthenes and aromatics as they change across the reactor bed heights. Hydrogen partial pressure effect on the product quality, aromatics and product yields were studied. It was found that an increase in hydrogen hydrocarbon ratio of 5.6 to 7.4, aromatics yield decrease from 58.5% to 55.5%, reformate yield increases from 52,805 kg/h to 53,234.5 kg/h, hydrogen yield increases from 10,955 kg/h to 14,515 kg/hr. The percentage weight of coke on the catalyst decreases with increase in hydrogen hydrocarbon ratio of 5.6 to 7.4 from 1.8%wt to 1.289%wt, 3.297%wt to 2.415%wt, 4.457%wt to 3.351%wt and 5.1850%wt to 3.983%wt for reactors 1, 2, 3 and 4 respectively.

Non Monotonous Product Distribution Dependence on Pt/γ‐Al2O3−Cl Catalysts Formulation in n‐Heptane Reforming.

AbstractThe synthesis of 19 carefully selected Pt/γ‐Al2O3−Cl formulations was followed by high‐throughput catalytic testing in order to unravel the effect of an active phase formulation change on n‐heptane reforming performances. Pt/γ‐Al2O3−Cl catalysts were prepared with different Pt (0.3–1 %wt) and Cl (0.1–1.4 %wt) contents and using two γ‐Al2O3 supports so that both sites concentrations and sites locations at the crystallite surface vary among the catalyst pool. Catalytic tests were conducted in mild conditions for a comparison of catalysts in kinetic regime. Results show that Pt and Cl concentrations control the competition between hydroisomerisation, hydrogenolysis and hydrocracking pathways. Aromatisation, on the contrary, is poorly affected by formulation changes. Non‐monotonous trends linking Pt/Cl ratio to isomerisation selectivity are found for both γ‐Al2O3 supports. This study provides new insights for the description of bi‐functional transformations in catalytic naphtha reforming.

Experimental Investigation and Kinetic Modeling of Naphtha Catalytic Reforming Using Pt-Re/Al2O3 Catalyst

Catalytic reforming is a process known in the refining industry to improve the quality of gasoline by increasing the octane number, the production of aromas and hydrogen production as a byproduct. The purpose of this research is to develop a kinetic model for naphtha catalytic reforming reactions with consideration of simple and reliable assumptions and also to provide a mathematical model using mass balance. In the kinetic model, 22 lamps and 48 reactions are present. Also, in the mathematical model, the superficial velocity of the fluid is considered variable in the axial direction of the reactor. In order to evaluate the proposed model, laboratory tests have been used in 24 different operating conditions, which according to the results of the analysis of the products, the yield of liquid is observed in the range of 0.701 to 0.952. Also, using experimental results, the model parameters are obtained through optimization with MATLAB software. Finally, the results of comparing the predicted product distribution through the model with their experimental values showed that the proposed model with acceptable accuracy could predict the distribution of the products.