Hydrodesulphurization Process Research Articles

Hydrodesulphurisation of Petroleum Coke

Hydrodesulphurisation in a fluidized bed offers the most attractive process for the desulphurisation of petroleum coke. Results of coke hydrodesulphurisation clearly indicate that the rate of sulphur removal is greatest at about 1100 K. The hydrodesulphurisation process is particularly effective with cokes of high sulphur content and high ash and heavy metals content, as at temperatures less than 1100 K the adverse effects of high ash and heavy metals content on desulphurisation is largely avoided. The process leads in general to increased porosity, density and surface area and improved reactivity. These properties are dependent on the sulphur concentration. The greater the amount of sulphur removed, the greater the structural changes expected in the coke treated. The weight loss is less than 10%.

The effect of acid treatment and calcination on the modification of zeolite X in diesel fuel hydrodesulphurization

AbstractFaujasite (X, Y) zeolites are considered the main and important catalysts in hydrorefining processes. In order to obtain zeolites with higher acidity and volume of mesopores, post‐synthesis modification, dealumination by different pickling techniques (using ethylenediamine tetraacetic acid [EDTA] chelating agent), and thermal treatment (calcination) were employed. The dealumination process led to the removal of the aluminum atoms from the zeolite structure and a rise in acidity while maintaining the zeolite crystalline lattice. X‐ray diffraction (XRD), atomic absorption spectrometry (AAS), Fourier‐transform infrared (FT‐IR), field‐emission scanning electron microscopy (FE‐SEM), Brunauer–Emmett–Teller (BET), and temperature‐programmed desorption of ammonia (NH3‐TPD) analyses were performed to study the physicochemical characteristics of the zeolite and catalysts prepared. Atomic absorption spectroscopy showed an increase in the Si/Al ratio in the modified zeolites. Measuring the surface area of zeolite and the volume of the pores through BET‐BJH and t‐plot methods indicated a reduction in the surface area and an increase in the volume of the pores. Under the influence of the dealumination process, the volume of the mesopores in the modified zeolites increased from 0.056 cm3 g−1 in the initial zeolite (Na‐X) to 0.2105 cm3 g−1 (zeolite X1). The acidity of the modified zeolites (X1) increased from 0.32–0.95 mmol NH3/g. The application of the catalysts containing X1 zeolite in the hydrodesulphurization (HDS) process yielded a product with less sulphur (conversion = 87.5%).

Recurrent Neural Network-Based Joint Chance Constrained Stochastic Model Predictive Control*

A novel recurrent neural network (RNN)-based approach is proposed in this work to handle joint chance-constrained stochastic model predictive control (SMPC) problem. In the proposed approach, the joint chance constraint (JCC) is first reformulated as a quantile-based inequality to reduce the complexity in approximation. Then, the quantile function (QF) in the quantile-based inequality is replaced by the empirical QF using sample average approximation (SAA). Afterwards, the empirical QF is approximated via an RNN-based surrogate model, which is embedded into the SMPC problem formulation to predict quantile values at different sampling instants. By employing the RNN-based approximation, the resulting deterministic optimization problem is finally solved through a nonlinear optimization solver. The proposed approach is applied to a hydrodesulphurisation process to demonstrate its efficiency in handling the SMPC problem.

Mutual inhibition effect of sulfur compounds in the hydrodesulfurization of thiophene, 2-ethylthiophene and benzothiophene ternary mixture

The hydrodesulphurization of a model component and equimolar ternary mixture of thiophene, 2-ethylthiophene and benzothiophene over sulphided CoMo/γ-Al2O3 and CoMo/γ-Al2O3-Nb2O5 catalysts were investigated in a fixed bed flow reactor. The catalysts were prepared by incipient wetness impregnation method and characterized by textural characteristics, total acidity and chemical species present on the catalysts surface. The characterization results showed that both CoMo/γ-Al2O3-Nb2O5 and sulphided CoMo/γ-Al2O3 catalysts exhibit a mesoporous structure with cylindrical pores open at both ends, evidenced by the IV type adsorption–desorption isotherm with a H1 hysteresis loop and have an average pore diameter between 3 and 4 nm. The chemical species present on the catalysts surface evaluated by XPS indicated that Co2+ and Mo4+ species are present in the sulfide form on both catalysts surfaces. In addition, there are also found oxidic species arising from incomplete reduction and sulphidation. The presence of niobium oxide in the catalytic support had a positive effect in leading to higher specific surface area (170 m2/g) and total acidity (0.421 meq/g) compared with CoMo/γ-Al2O3 catalyst (140 m2/g and 0.283 meq/g) respectively. The evaluation results from the hydrodesulfurization showed that CoMo/γ-Al2O3-Nb2O5 catalyst had a higher activity in hydrodesulphurization process of thiophene, 2-ethylthiophene and benzothiophene. The CoMo/γ-Al2O3-Nb2O5 catalyst eliminated sulfur from the single component feed (corresponding to 2380 ppm S) and reduced below 10 ppm, for the feed consisting in the equimolar ternary mixture of thiophene, 2-ethylthiophene and benzothiophene (2380 ppm S). The reactivity of thiophen compounds was reduced due to competitive adsorption. It was observed that benzothiophene inhibits the transformation of thiophene and 2-ethylthiophene. A mutual inhibition effect between sulfur compounds was also observed when thiophene, 2-ethylthiophene and benzothiophene were combined and tested over the CoMo/γ-Al2O3 catalyst. The inhibition effect had a lower intensity by introducing Nb2O5 in the catalyst support.

Modelling of hydrodesulphurization in industrial trickle bed reactor using mixing cell network approach

AbstractA mixing cell network (MCN) was developed for the commercial diesel hydrodesulphurization process (DHDS) in a trickle bed reactor (TBR). The two‐phase model is developed to simulate the performance of an industrial DHDS unit. Major hydrotreating reactions such as hydrodesulphurization (HDS), hydrodearomatization (HDA), and olefin saturation were accounted for in the developed model. The MCN model predictions on axial concentration profiles of sulphur, polynuclear aromatics (PNAs), monoaromatics (MAs), and temperature were found to be in agreement with the real‐time plant data. Further, the predicted results were also compared with the plug flow model to confirm model adequacy. The results obtained in this paper show the efficacy of the MCN model in simulating multiple reactions happening in real industrial scenarios.

A Comparative Study on SECA Compliance Options for Maritime Fuel Producers

In January 2015, the Sulphur Emission Control Areas (SECA) regulations changed so that ships that ply the Baltic Sea and the North Sea can no longer use bunker fuel that exceeds 0.1 per cent v/v of sulphur. Many changes have been seen in the maritime sector, especially in the Baltic Sea region (BSR). From studies, the impact is still somewhat negative for some maritime stakeholders, such as small-scale fuel producing companies who must produce fuel that complies with the SECA requirements. The impact analysis of their compliance options shows that hydrodesulphurisation (HDS) option is the most viable option with a commensurable investment return rate, but it is highly risky and expensive considering the incessant plummeting of fuel price and the financial status of such companies. However, even though the situation looks bleak for the small-scale maritime fuel producers, a deeper probe revealed a chance for exceptional opportunities for growth and profit through a change of business model to the maritime energy-contracting model (MEC). The study zooms in on a case study of a fuel producing company and empirically compares the operating costs of the MEC model (as a decentralised option) and the HDS process (as a centralised option) to determine which option will be most economically worthwhile if adopted as a SECA compliance strategy to ensure a rounded and robust choice-making process for maritime stakeholders in such situations.

Comparative Study Between two Reaction Kinetic Mechanisms of Thiophene Hydrodesulphurization over CoMo /gama - Al2O3 Supported Catalyst

The kinetic study of the thiophene hydrodesulphurisation process was carried out for CoMo/gama-Al2O3 catalyst, at temperatures between 175 and 275 �C, pressure ranged from 30bar to 60 bar and the liquid hourly space velocity from 1h-1 to 4 h-1. For the reaction mechanism, the Langmuir-Hinshelwood-Hougen-Watson model (LHHW) was used and two kinetic models were proposed: the first model, that considered that H2 is adsorbed on a different type of active center than thiophene and the second model, that considered that the two reactants are adsorbed on the same type of active sites. The values obtained for the average relative error (ARE) and the correlation coefficient between the experimental and the calculated data (R2) indicate that the Langmuir-Hinshelwood model, describing the adsorption on two active sites, best describes the kinetics of the thiophene hydrodesulfurization reaction over CoMo/gama-Al2O3 tested catalyst.

Entrepreneurial compliance opportunities for maritime fuel producers

In January 2015, the Sulphur Emission Control Areas (SECA) regulations changed so that ships that ply the Baltic Sea and the North Sea must no longer use bunker fuel that exceeds 0.1%. After the regulation of many compliances, changes occurred in the maritime sector, especially in the BSR. From studies, the impact is still somewhat negative for some maritime stakeholders such as small-scale fuel producing companies who must produce fuel that complies with the SECA requirements. The impact analysis of their compliance options shows that hydrodesulphurisation option is the most viable option with a commensurable investment return rate, but it is highly risky and expensive considering the incessant plummeting of fuel price and the financial status of such companies. However, even though the situation looks bleak for the small-scale maritime fuel producers, a more in-depth probe revealed a chance for exceptional opportunities for growth and profit through a change of business model to the maritime energy-contracting model (MEC). The study zooms in on a case fuel producing company, empirically considers and compares the MEC model (as a decentralised option) and the hydrodesulphurisation process (as a centralised option) and, if either option is adopted by as a SECA compliance strategy to ensure a rounded and robust choice making-process for maritime stakeholders in such situations.

Ionic liquid [BMIM][Cl] immobilized on cellulose fibers from pineapple leaves for desulphurization of fuels

Industrial combustion of fuels containing sulfur is responsible for most of the greenhouse gases in the atmosphere. The high impact of fuels is mainly on the content of aromatic S-compounds. These compounds are hard to remove through conventional hydrodesulphurization (HDS) processes because of their refractory properties and high boiling points. In this research, we are reporting the preparation, characterization, and evaluation of a cheap, regenerable and reusable composite based on the ionic liquid 1-butyl-3-methylimidazolium chloride immobilized on a renewable matrix of natural cellulose fibers. Characterization of the composite included FTIR, TGA, SEM, and XDR. The extraction capacity of thiophene and benzothiophene of the synthesized material was evaluated in synthetic mixes in isooctane and monitored by GC-FID. We achieved removal percentages of up to 62% of total sulfur from a model oil with an initial concentration of 458 mg S/L.

Prediction of Sulfur Content in Desulfurization Process Using a Fuzzy-Logic Based Model

In petroleum industry, hydrodesulphurization (HDS) process is considered as one of the crucial catalytic units in which the sulfur is mostly eradicated. The modeling of HDS process is very important for the proper understanding of the process operation to be optimized. The studies conducted, in this area, focused on predicting parameters using analytical, empirical and numerical approaches. However, a typical desulfurization process is constantly faced with an uncertainty, which should be considered in a reasoning way. Therefore, this work aims to explore the use of fuzzy logic (FL) inference system in creating models of the HDS process for the prediction of sulfur reduction from oil. In order to validate the proposed model, we employed experimental data from the HDS setup. The simulated sulfur content results obtained from the proposed model correspond closely to the real experimental values. The outstanding performance of the developed FL-based model suggests its potential in predicting sulfur content for optimization of the HDS process. The model demonstrates promising results in terms of high correlation (R2=0.98) and minimal percentage of error (AARE=0.072).

Influence of technological parameters and hydrogen-containing gas consumption on the efficiency of middle distillates hydrodesulphurization process

This paper presents the results of a study of the influence of process parameters (contact time, temperature and pressure) and hydrogen-containing gas consumption on the efficiency of catalytic hydrotreating of middle distillate fractions, performed using a mathematical model of the process. It was found that with the increase in the contact time of the raw material with the catalyst, the concentration of sulfides decreases more rapidly than the concentrations of benzothiophenes and dibenzothiophenes. The degree of conversion of sulfides, benzothiophenes and dibenzothiophenes increases with the process temperature in the range from 350 to 425 °C by 39.9; 37.5 and 19.4%, respectively. The greatest degree of desulfurization is achieved by simultaneous increase in pressure and temperature. Thus, at a temperature of 430 °C, an increase in pressure from 2.0 to 4.0 MPa leads to a decrease in the residual sulfur content from 230 to 13.5 ppm. With an increase in the consumption of hydrogen-containing gas from 42,000 to 50,000 m3/h, the efficiency of the hydrotreating process of the middle distillate fractions increases (the residual content of total sulfur in the hydrotreating product decreases from 55.9 to 24.8 ppm).

Hydrogen production from oil sludge gasification/biomass mixtures and potential use in hydrotreatment processes

Gasification of oil sludge (OS) from crude oil refinery and biomass was investigated to evaluate hydrogen production and its potential use in diesel oil hydrodesulphurization process. Gasification process was studied by Aspen Hysys® tools, considering different kinetic model for main OS compounds. Air and superheated steam mixtures as gasifying agents were simulated. Gasification parameters like: temperature, syngas chemical composition and gas yield were evaluated. Results showed OS thermal conversion needs a working temperature above 1300 °C to ensure a high conversion (>90%) of OS compounds. Thermal energy requirement for gasification was estimated between 0.80 and 1.25 kWh/kg OS, considering equivalence air (ER) and steam/oil sludge (SOS) ratio between 0.25-0.37 and 0.2–1.5 kg steam/kg OS, respectively. The gas yield was 2.28 Nm3/kg OS, with a H2 content close to 25 mol%, for a H2 potential production about 1.84 Nm3 H2/kg OS; nevertheless, when OS and biomass mixtures are used, hydrogen production increases to 3.51 Nm3 H2/kg OS, meaning 37% of H2 (from natural gas) required for diesel oil hydrodesulphurization could be replaced, becoming an added value technological alternative for OS waste conversion as a source of H2, inducing a considerable reduction of greenhouse gases and non-renewables resources.

Hydrogen production by methane and hydrogen sulphide reaction: Kinetics and modeling study over Mo/La2O3–ZrO2 catalyst

Actually, catalytic steam reforming method is a widely used to produce hydrogen or syngas as the first step for the conversion of methane into liquid fuels through the Fischer-Tropsch synthesis.The reforming of CH4 by H2S can be considered as an alternative route to produce hydrogen from methane. With this process, the removal of H2S in natural gas streams is no longer necessary and sulfur, usually considered as a strong pollutant on liquid fuels in refineries, is used as a reagent in H2S form of hydrodesulphurization processes. This alternative produces hydrogen, a valuable chemical and clean energy source, as the principal product and carbon disulphide as a secondary petrochemical with high commercial value.The open literature concerning the kinetic study of the methane-hydrogen sulphide reaction is very poor. In this research the reaction of CH4 and H2S over zirconia catalyst modified with lanthanum oxide impregnated with molybdenum has been studied in a fixed bed tubular reactor varying the inlet CH4 flow rate over a temperatures range of 1023–1323 K and feed molar ratio CH4:H2S of 1:12. The Langmuir–Hinshelwood theory has been used to analyze kinetic models. Model discrimination has been performed and the kinetic parameters and adsorption constants calculated.Finally, the simulation process of reforming CH4 by H2S has been developed in which separation of the produced hydrogen and no reacted H2S involves absorption through diethanolamine. A tubular reactor from kinetic parameters was dimensioned. Aspen Plus ® 11.1 and Hysys V.8 simulation software was used. Preliminary results showed a high purity H2 can be produced by this route.

Study of the Hydrodesulphurization Process of Hydrogenate of Shubarkol Coal

This is a research on the hydrodesulphurization process of hydrogenate from the coal of Shubarkolsky deposit (Republic of Kazakhstan) in the presence of pyrite and natural zeolite. The rate constants for hydrodesulphurization process of the liquid products and Gibbs energy were calculated by the method of equilibrium kinetic analysis, which was necessary for improving the technological parameters for the hydrotreatment of liquid hydrogenation products. It is shown that the optimal time of the hydrodesulphurization process is 15-25 minutes. The sulfur content in the fraction up to 2000С is 0.043 %, and in a fraction of 200-3000С - 0.065 %, which indicates a high degree of hydrotreatment of the hydrogenate in the presence of the above mentioned catalyst.

Effect of sulphur vacancy on geometric and electronic structure of MoS2 induced by molecular hydrogen treatment at room temperature

Investigations into the interaction between molecular hydrogen and molybdenum disulphide have been in increasing demand to improve the understanding of the hydrodesulphurisation process, especially the creation of sulphur vacancies which result in coordinatively unsaturated sites in MoS2. Here we present comprehensive studies of the structural and electronic modulation caused by exposure of MoS2 to H2 over a low temperature range, which may be helpful for industrial applications. Detail investigations were conducted with Raman spectroscopy, high resolution transmission electron microscopy (HRTEM), and electrical transport properties as a function of H2 gas pressure up to 24 bar from 295 K to 350 K. Upon exposure to H2, we observed bond-softening using Raman spectroscopy, a decrease in d-spacing from the TEM results, and an increase in conductance, all of which are consistent with the first-principles calculations. The results demonstrate the formation of sulphur vacancies even under low H2 pressure at low temperature.

Intensification of hydrodesulphurization process with a structured bed spiral mini-reactor

The procedure followed for the study of the characteristics of the intensification of catalytic hydrodesulphurization process with a structured bed spiral reactor is presented in the current work. This procedure consists of two parallel experimental methods investigating the mechanisms involved in the operation of the reactors. The first method aims at the study of the process mechanisms with mock up experiments at ambient conditions using systems with inorganic or organic liquids, water or heptane, and oxygen or nitrogen as gas phase. The second one focuses on the mechanisms at reaction conditions using simple model reactions, like benzene hydrogenation. The studied mechanisms with the methods followed are the fluid dynamic characteristics of the operation of spiral reactor, flow regime, axial dispersion and mass transfer limitations. The mass transfer limitations were also studied with desulphurization experiments taking into account the impact of the inhibitors hydrogen sulphide and ammonia on the desulphurization reaction.

HAZOP Analysis Management System with Dynamic Visual Model Aid

Problem statement: Ensuring safe operability and minimizing risk is the key component to prevent negative impact in all industries dealing with toxic, reactive, flammable and explosive. Hazard and Operability (HAZOP), a preliminary and systematic approach for identifying hazards has been unquestionably successful in reducing incidents by mitigating the consequence of major accident in the industries process facility. However, laborious work, time and cost are the shortcoming in performing and maintaining HAZOP analysis. Many research works over HAZOP automation available yet the traditional approach is still widely used by plant operators as it covers all part and aspect of a specific plant rather than generalizing to fit many plant types. Approach: In this study, we presented web based HAZOP analysis management system to help HAZOP team and related individual to perform revision, tracking and even complete HAZOP analysis without management bureaucracy. Besides depend solely to expert imaginative thinking of scenario using P&ID, We added dynamic visual model to bring the system user a different view of consequent and subsequent to an accident and can be analyzed in three dimensional effects. This prevented miss looks due to 'paper based' view. Similarity matrix is responsible ensuring accuracy in analysis tracking. Reactor section in a hydrodesulphurization process was used as the case study to illustrate proposed system performance. Results: Developed system in average manages to reduce more than half the time required in performing HAZOP analysis compares to traditional method. Conclusion: This system expected to be the base engine for Virtual Reality simulator in analyzing accident caused by human factor

Testing the impact of hydrodesulphurisation process parameters on diesel fuel properties

In this work the influence of changes in hydrodesulphurisation (HDS) process parameters (space velocity and temperature) on efficiency of sulphur compounds removal was tested. The feedstock, straight run gas oils (STGO) from Croatian crude oil used for diesel fuel production have been subject to the hydrodesulphurisation process with Co-Mo/Al2O3 commercial catalyst in a trickle bed reactor in high-pressure apparatus at the following conditions: total reactor pressure of 500 kPa, reactor inlet temperature in the range 330 - 355 °C, liquid hourly space velocity (LHSV) in the range 2.0, 2.5 and 3.0 h-1 and hydrogen/hydrocarbons ratio of 120. The laboratory high-pressure apparatus was upgraded by implementation of a modern computer-based control system. Control system supports experimentation aiming better process conditions monitoring and control with the purpose of improved repeatability and achievement of safe operation.

Deashaltening and Hydrodesulphurization of Jumboor Vacuum Residue

Vacuum residue of Jumboor crude oil above 773 K of specific gravity 1.105 and 6. I wt% sulfur , was treated with commercial pentane &hexane fractions for preparing deasphaltened oil (DAO) suitable for hydrodesulphurization process. Solvent deasphaltening was examined with mixing time 0.25 to 4 h and solvent to oil ratio 4 to 15 ml : 1g at different temperatures . The asphaltenes yield was decreased with increasing mixing time and increased with increasing solvent to oil ratio . Hexane deasphaltened oil hydrotreated on presulfided commercial cobalt-molybdenum alumina catalyst at specified operating conditions in a trickle bed reactor . The hydrotreating process applied at a range of temperatures varied from 623 to 698 K, liquid hourly space velocity (LHSV) from 0.7 to 2.2 h-1 ,H2/oil ratio about 300 liter/liter and hydrogen pressure was 4 Mpa . The results of hydrotreating process indicate high sulfur and metal removal with decreasing LHSV as well as high temperature applied . The kinetic of hydrodesulphurization and demetalization reactions followed 2nd and 1st order reactions respectively .

On novel processes for removing sulphur from refinery streams

This review discusses some of the processes that have been, or are being, developed as an alternative/addition to present-day hydrodesulphurization processes that are based on (selective) heterogeneous catalysis. The technologies applied in these alternatives range from reactive adsorption, oxidative routes (especially for diesel) and other chemical conversion methods, to “simple” physical separation methods (non-destructive adsorption, extraction, etc.). It is concluded that it appears that for the time being, as long as sulphur levels of 10 ppmw or slightly below are aimed at, the classical hydrotreating options and their off shoots still hold the field of transportation-fuel desulphurization, although a few of the possible alternatives do have achieved commercial status in the gasoline area. If, on the other hand, S in product levels should be as low as <1 ppmw, then polishing processes will come into their own.