Catalytic Naphtha Research Articles

The influence of pore-architecture over n-heptane cracking using MFI, *BEA and MSE zeolite catalysts: Multipore versus hierarchical porosity

The catalytic properties of zeolitic materials are governed by the intricate interplay between catalytic and transport processes, which, in turn, depend critically on the topology and morphology features. Here, the catalytic performance of typical three dimensional zeolites, including medium pore MFI, large pore *BEA and multi-pore MSE topologies with comparable Si/Al ratios are employed as n-heptane cracking catalysts to inspect the influence of topology on product slates for naphtha molecules. Furthermore, a bead-milling coupled with porogen assisted recrystallization method is used to fabricate hierarchically porous MSE zeolite for the first time. The catalytic n-heptane cracking properties of hierarchical MSE zeolite are compared with the hierarchical MFI and *BEA analogues, derived from the cracking mechanism ratio and the hydrogen transfer coefficient, respectively, to exam the influence of transport on product distributions. Multi-pore MSE zeolite outperforms MFI and *BEA zeolites in terms of light olefin selectivity and yield, owing to an exaggerated contribution from Haag-Dessau mechanism mediated cracking and a reduced probability for side-reactions, as a consequence of decreased residence time for the primary cracking product olefins. The developed methods to fabricated hierarchical zeolites and the revelation of structure-catalysis relationship may inspire future catalyst design for catalytic naphtha cracking.

Challenges for Selective Catalytic Naphtha Reforming Products Using Response Surface Methodology (RSM)

Challenges for Selective Catalytic Naphtha Reforming Products Using Response Surface Methodology (RSM)

Maximizing light olefin production via one-pot catalytic cracking of crude waste plastic pyrolysis oil

Energy-efficient processes for converting polyolefinic waste plastics into light olefins are critical for mitigating environmental pollution and reducing carbon emissions. In this study, an alternative recycling scheme, the catalytic cracking of crude waste plastic pyrolysis oil (WPPO) over microspherical P-modified steam-treated ZSM-5 (ms-P-HZSM5-S), was demonstrated and compared to a state-of-the-art commercial scheme, the thermal cracking of a hydrotreated naphtha range of WPPO. The C2–C4 olefins yield achieved by the catalytic WPPO cracking (56.6 wt%) exceeded those achieved by the thermal WPPO cracking (36.1 wt%), thermal naphtha cracking (23.1 wt%), and catalytic naphtha cracking (29.7 wt%), which indicated the superiority of WPPO over naphtha as a feedstock. However, during a deactivation test over ms-P-HZSM5-S, coke accumulation resulted in a rapid decline in the yields of ethylene (from 17.2 to 14.6 wt%), propylene (from 25.8 to 23.6 wt%), and benzene, toluene, and xylenes (from 16.1 to 13.4 wt%) after a reaction time of 810 s (temperature = 680 °C, weight hourly space velocity = 16 h−1). Nevertheless, the catalytic performance was fully restored through regeneration in air at 730 °C, which confirmed the viability of continuous operation involving successive reaction–regeneration cycles. These findings can be leveraged to devise a new approach, the catalytic cracking of WPPO integrated with a continuous regeneration (e.g., circulating fluidized bed reactor) system, which could offer several advantages over the commercial strategy, including the posttreatment-free utilization of the entire WPPO range, higher light olefins yields, continuous coke removal, reduced energy consumption, and non-necessity of H2.

Identification of the Effect of Mass Flow Rate and Hydrogen to Hydrocarbon Ratio on the Thermal Performance of a Shell and Tube Heat Exchanger – An Industrial Case Study

In various industrial processes such as petroleum refineries, crude oil must be heated to the required temperature. Here a study of a heat exchanger problem of a catalytic naphtha reforming unit of an SKIKDA refinery (RA1K) is carried out. In this unit the feed (naphtha and recycle gas) is required to enter the first reactor of the reaction section at 471℃, while the feed inlet temperature at the reactor is only 450℃. This problem appeared after starting the unit with a mass flow of 60% of the naphtha. The essential device for heating the charge before entering the reactor is shell-and-tube heat exchanger. In the present study, the Kern method is used to check the heat exchanger in the design and experimental cases. The Aspen HYSYS software has been used to study the influence of various naphtha mass flow rates on the thermal performance of a heat exchanger. The outlet feed temperature was examined for each mass flow rate of naphtha (i.e., 60, 70, 80, 90 and 100%). The simulation results show the important role of the studied parameters in the thermal performance enhancement of heat exchanger, where the case of a mass flow of 60% of the naphtha, the temperature 471℃, provided for by the design, is obtained with an H2/HC ratio of 4.68.

Simulation of packed bed reactors for naphtha reforming unit

The study focused on the performance evaluation of catalytic naphtha reforming unit via a packed bed reactors arranged in series. Three series arranged packed bed naphtha reforming reactors were developed and simulated using Aspen hysys software and steady state performance models of the packed bed naphtha reforming reactor were developed through the application of the principle of conservation of mass and energy to predict both the yields of theses reactors, their dimensions in terms of length, diameter, height, volume and temperature effects or progressions along the reactors’ length respectively. Three main reaction paths were considered in this research study that include the conversion of naphthenes to aromatics, naphthenes to paraffins and hydrocracking of paraffins. The developed performance models yielded first order ordinary differential equations which were solved using Runge-Kutta fourth order ODE45 solver. The packed bed reactor operating conditions of temperature and pressure are between 4800C and 5200C and 2atm respectively with ninety percent (90%) conversion. The simulated reactor performance model for the three reactors yielded 29.7 m3, 40.78 m3 and 52.33 m3 for reactor volume, catalyst bed height of 11m, 12.98 m, 16 m, and reactor’s diameter of 1.85 m, 2 m and 2.04 m respectively.

Monitoring and path optimization of catalytic reformer in a refinery: Principal component analysis and A* algorithm application

Catalytic naphtha reforming converts naphtha into gasoline or aromatics and is a vital petrochemical process in refineries. This paper developed a hybrid framework combining principal component analysis (PCA) and A* algorithm to find optimal operating conditions through process monitoring and path optimization. PCA is employed to develop an efficiency monitoring model using the process history data. The operating conditions with profit information are projected onto a two-dimensional plane using the first and second principal components. High- and low-profit intervals can be clearly distinguished on this map. The A* algorithm is then employed in finding an optimal trajectory from low-index to high-index on the projection map. Finally, the inverse transformation is used to obtain optimum variables for optimal operating conditions. The effectiveness of the proposed framework is verified by applying it to a Sinopec refinery.

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.

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.

Fuzzy logic control of a catalytic naphtha unit

This work examines the fuzzy logic-based control of a catalytic reformer. The control process requires development of an exact process model valid over a wide range of operating conditions. Two control methods, proportional integral derivative (PID) and Fuzzy-PID, were applied to determine the optimal operating conditions. The output temperature from the feedback fuzzy controller was sent to the PID controllers as a setpoint in the heating system loop, and two fuzzy logic systems, one in the forward path and one in the feedback path were developed to give setpoints for temperature control loops in the four reactors. A fuzzy logic-based optimal control scheme was established to increase the aromatics yield, subject to constraints on the inlet temperature of the reactors. A rigorous kinetic model was then developed by expressing the heat and mass balances under unsteady state conditions. This model was used to determine the temperature and concentration profiles of three main hydrocarbons, naphthenes, paraffins, and aromatics, across the four reactors. A reaction scheme involving 27 pseudo components connected using a network of 71 reactions for components in a wide range of carbon numbers was thus modelled. The simulation results for the model were compared with previous studies to validate the model, and good agreement was found between the reformate composition of the proposed model and the plant reformate composition and temperature. The simulation results also showed that the PID –Fuzzy controller is accurate but that it requires additional time to reach a steady state value.

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.

Taking advantage of the excess of thermal naphthas to enhance the quality of FCC unit products

Today, many European refineries finish up with excess of low-quality thermal naphthas that are hard to be marketed and, commonly, end being absorbed by catalytic naphthas at the expense of their higher quality. In this context, we propose to investigate the suitability of co-feeding thermal naphthas, i.e. visbreaker and heavy coker naphtha, with vacuum gasoil (VGO) to the fluid catalytic cracking unit. A riser simulator reactor has been used in the experimentation and tested conditions have been: 500 and 550 °C; C/O mass ratio, 6 gcat goil−1; and, residence time, 3 − 12 s. Products have been lumped according to the fractionation made in refineries in: dry gas, liquefied petroleum gases, gasoline, light cycle oil and coke. The results reveal that the co-feeding of any of the naphthas hinders the over-cracking increasing the contents of gasoline and that it inhibits the condensation reactions that produce coke. Two main factors contribute to these results: (i) the competitive adsorption and reaction between the components of the naphthas and the VGO; and (ii) the shortening of the residence time caused by an increase of the flow when the naphtha is co-fed. It should be highlighted the variation in the composition of the gasoline produced with the blends, with overall reductions of the contents of olefins and aromatics.

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.

A conceptual comparison between potential configurations in the thermal coupling of naphtha reforming with propane ammoxidation

Abstract In order to achieve a proper temperature profile and consequently a higher production rate, the conventional catalytic naphtha reforming process (CNR) was coupled thermally with the propane ammoxidation process as a heat source through a novel bifunctional reactor. Propane ammoxidation is a highly exothermic process that occurs on the reactor tube side to supply the required heat for naphtha reforming reactions on the shell side. In this study, the performance of the novel reactor with different types of feeding has been investigated. Two possible counter-current configurations of Series-Naphtha-Parallel-Ammoxidation (SNPA) and Parallel-Naphtha-Parallel-Ammoxidation (PNPA) have been compared with four possible co-current configurations of SNPA, PNPA, Series-Naphtha-Series-Ammoxidation (SNSA), and Parallel-Naphtha-Series-Ammoxidation (PNSA). Among the co-currents, PNPA showed the highest production. The counter series feeding of propane ammoxidation (SNSA and PNSA) was not possible due to the exothermic side's temperature runaway. The results showed that the counter-current SNPA arrangement significantly boosts the heat transfer between the endothermic and the exothermic sides, improving the product yields more than other arrangements and CNR. For counter-current SNPA 42% yield of aromatics was achieved, which is 5% and 7% more than the co-current PNPA and CNR, respectively. In addition, co-current and counter-current configurations were investigated in terms of temperature uniformity. The best configurations in co-current and counter-current were co-SNSA and count-SNPA, respectively. Also, optimization of counter-current SNPA was examined and its results compared with non-optimized results. It was observed that in optimized reactors, the yield of aromatics and the overall yield of acrylonitrile (ACN) were increased to 45% and 41%, respectively.

Detailed description of the mathematical modeling of the catalytic naphtha reforming process dynamics

This work is dedicated to the construction of a kinetic model for the naphtha reforming process. By assembling the components into reactivity based lumps, a new reaction network model rooted on 33 lumps and 101 reactions was studied. The tabu search algorithm was used to determine the global optimal solution. The experimental data from the laboratory scale isothermal reactor was used to investigate the kinetics. By comparing with the test data, the average deviation of the reformed products calculated from the proposed model reached 2.5%.

Analysis of combined heat and mass transfer in membrane-assisted thermally coupled reactors containing naphtha reforming and m-xylene hydrodealkylation

In this work, the performance of catalytic naphtha reforming in the thermally coupled membrane reactors has been investigated. It is suggested that the hydrodealkylation of m-xylene be placed in the tube side and the catalytic reforming in the shell side of the proposed reactor. The interior reactor wall has been made of palladium membrane, which permits the hydrogen to penetrate from the shell side with higher partial pressure to the tube with lower partial pressure. Thermal coupling of hydrodealkylation of m-xylene with naphtha reforming, as well as the removal of a part of the hydrogen as a by-product from the reforming side leads to an increase in reformate production. Simulation results indicate that the aromatic production rate in this configuration increases by 16.43% relative to the membrane reactors and by 23.52% relative to the conventional reactors. The effect of parameters including the membrane thickness, inlet temperatures of naphtha and HDA feeds, the molar flow rate of the hydrodealkylation side, the hydrogen to hydrocarbon molar ratio and also, the catalyst deactivation on the performance of the system has been studied. Finally, in order to improve the performance of thermally coupled membrane reactors, the effective parameters in the proposed configuration have been optimized by the genetic algorithm. The yield of aromatic was enhanced by about 14% by this optimization. Also, the conversion of m-xylene in each bed was improved in optimized thermally coupled membrane reactors.

Real-Time Semisupervised Predictive Modeling Strategy for Industrial Continuous Catalytic Reforming Process with Incomplete Data Using Slow Feature Analysis

The catalytic naphtha reforming process is one of the most significant processes in the petrochemical industry. This process is notable for its function of transforming petroleum refinery naphtha f...

Modelling, simulation and sensitivity analysis of naphtha catalytic reforming reactions

In this paper, a model of catalytic naphtha reforming process of commercial catalytic reforming unit of Kaduna Refining & Petrochemical Company (KRPC) is adopted and simulated using the gPROMS software, an equation-oriented modelling software. The kinetic and thermodynamic parameters and properties were obtained from literature. The model was used to monitor the behaviour of the temperature and concentrations of parafins, naphthenes and aromatics with respect to the changing heights of the reactors. A comprehensive sensitivity analysis of the product quality (Aromatics) and product yield, reformate, lighter gases and hydrogen yields is performed by varying the operating conditions of the reaction and the following conclusions were made. It was found that the production of aromatics, hydrogen yield, lighter gases and coke on catalyst increase with increasing temperature of the reaction while the reformate yield decreases with the increasing temperature and vice versa. The aromatics, hydrogen yield, coke on catalyst and lighter gases decrease with increasing pressure while the reformate yield decreases with decreasing pressure and vice versa. Hydrogen-hydrocarbon ratio (HHR) affects the product quality slightly by increasing the reformate and hydrogen yield and decreasing the aromatics slightly as well decreasing the coke on catalyst.

Energy saving measures from their cradle to full adoption with verified, monitored, and targeted performance: a look back at energy audit at Catalytic Naphtha Reforming Unit (CCR)

Intending to contribute to the discourse about industrial energy efficiency and barriers to its improvement, deep insight into the scope and methodology and achievements of an energy audit on a Catalytic Naphtha Reforming Unit are provided. The audit of this particular unit was a part of the audit of the whole SLOVNAFT refinery in 2010–2012. The audit itself is the preparation of saving proposals’ implementation and post-implementation monitoring and targeting that lasted until spring 2016 covered in retrospective as the auditors were involved in all post-auditing phases as well. Several saving ideas emerging from the performed audit were rejected or have still not been implemented due to either technical issues or non-technical factors. Implemented proposals included improvement in the condensates’ management system, boiler feedwater preparation, and increased exploitation of the cogeneration potential. A cumulative 3-year benefit of over 600 k€ is reported which is close to the targeted value. The post-audit cooperation of auditors with the refinery’s staff enabled to define the non-technical barriers to saving proposals’ adoption that are of general nature. These included (1) short payback period requirement, (2) possibility of implementation of changes during the turnaround/general revisions, (3) conflicting relationships between local micro-economies of production units and the net-economy of the whole refinery, (4) internal processes and communication, and (5) personnel policy. Long-term cooperation, winning the trust and support of the staff and managers, and regular monitoring and targeting of implemented measures are seen as essential parts of sustainable industrial energy efficiency improvement in any industrial energy auditing.