ABSTRACT Thiols in liquefied petroleum gas are undesirable due to their foul odor and corrosive n... more ABSTRACT Thiols in liquefied petroleum gas are undesirable due to their foul odor and corrosive nature. The process of removing these thiols is termed as sweetening. Metal phthalocyanines are reported to be the most effective sweetening catalyst. However, the solubility of metal phthalocyanine is low in aqueous medium. Thus, in an effort to further improve upon the existing catalysts, a novel cobalt phthalocyanine sulfonamide catalyst was developed. Laboratory and commercial evaluation of this catalyst showed enhanced activity as compared to a commercial catalyst with comparable stability. With proven higher activity, comparable stability, design of grass root oxidizer using this catalyst is the next step. Design of oxidizers for an extractive sweetening process based on this catalyst in grass root refineries requires a rigorous kinetic model. The paper reviews the literature on sweetening kinetics and focuses on the concepts of design of laboratory reactors for reaction kinetics studies for such gas-liquid reactions. Laboratory reactor systems can be useful for accurate estimation of kinetic parameters which can then be used to design industrial reactors and predict their performance.
Magnetically separable layered double hydroxide MgAl–LDH@Fe 3 O 4 composite supported cobalt phth... more Magnetically separable layered double hydroxide MgAl–LDH@Fe 3 O 4 composite supported cobalt phthalocyanine catalyst was synthesized and used for the aerobic oxidation of mercaptans to corresponding disulfides under alkali free conditions. The catalyst exhibited excellent activity for the oxidation of mercaptans using molecular oxygen as an oxidant which can be effectively recovered by using an external magnetic field. In addition, the covalent immobilization of cobalt phthalocyanine to MgAl–LDH@Fe 3 O 4 support prevents the leaching of the catalyst and improves its activity and stability.
Tune up the 'sweetening' process for your facility Novel catalysts can improve the oxidation of t... more Tune up the 'sweetening' process for your facility Novel catalysts can improve the oxidation of thiols (RSH) found in light oils. Thiols in petroleum products, such as liquefied petroleum gas (LPG) and light straight-run naphtha (LSRN), usually found as light RSH compounds. They are undesirable, have a foul odor, and are highly corrosive. Light RSH can also affect the activity of catalysts for downstream processes. The process for removing thiols is referred to as "sweetening. " The thiols are catalytic oxidized to less deleterious disulfides. 1 The light RSH is first extracted with an aqueous caustic solution to form mercaptides, as shown in Eq. 1. The subsequent salts (NaSR) are oxidized in the presence of a catalyst and air to organic disulfides (RSSR) as shown by Eq. 2. The overall reaction can be represented as:
Hydrodesulfurization (HDS) of straight-run naphtha (SRN) reformer feed significantly improves ref... more Hydrodesulfurization (HDS) of straight-run naphtha (SRN) reformer feed significantly improves reformer catalyst life, gasoline yield, and its stability. HDS of SRN helps in protecting the expensive platinum-based reforming catalyst. HDS is usually catalyzed by sulphided Co-Mo/Al 2 O 3 or sometimes Ni-Mo/Al 2 O 3. The design of naphtha HDS units requires the development develop a kinetic model. It is well-known that among the sulphur types present in naphtha, the most persistent sulphur compound is thiophene. Therefore, the design of naphtha HDS units is governed by thiophene HDS rates. It is essential to have experimental conditions free from intraparticle diffusional limitations in order to obtain intrinsic kinetics data. This Communication discusses the calculation procedures involved in ensuring experimental conditions free from pore diffusional resistances before conducting detailed kinetics studies. The pore diffusional resistance was quantified in terms of Thiele modulus (F).
ABSTRACT Novel magnetic silica beads functionalized cobalt phthalocyanine catalyst was prepared b... more ABSTRACT Novel magnetic silica beads functionalized cobalt phthalocyanine catalyst was prepared by immobilization of the sulfonated Co(II) phthalocyanine (CoPcS) on the amino functionalized silica coated magnetic nanoparticles (Fe3O4@SiO2, SMNP) via a sulfonamide linkage. The developed catalyst was characterized by various techniques such as XRD, N2 adsorption-desorption, UV-Vis, FTIR, SEM and TGA analyses. The synthesized catalyst was found to be effective in oxidation of mercaptans in an aqueous medium by using molecular oxygen as oxidant under alkali free conditions. The efficient recovery by using an external magnet along with reusability of the catalyst in an alkali free reaction condition makes this methodology a facile, clean, effective and economically feasible approach for the oxidation of mercaptans to disulfides.
In order to meet environmental norms, Indian fuel policy aims at producing ultra low sulphur dies... more In order to meet environmental norms, Indian fuel policy aims at producing ultra low sulphur diesel (ULSD) in near future. A catalyst for meeting such requirements has been developed and kinetics of this catalytic process is being looked into. In the present investigations, effect of mass transfer on kinetics of ultra deep hydrodesulphurization (UDHDS) to produce ULSD has been studied to determine intrinsic kinetics over a pre-sulphided catalyst. Experiments have been carried out in a continuous flow micro reactor operated in the temperature range of 330 to 360 0 C, whsv of 1 hr -1 at a pressure of 35 bar, and its parameters estimated. Based on the derived rate expression and estimated parameters optimum operation range has been determined for this UDHDS catalyst to obtain ULSD product.
ABSTRACT Performance prediction by use of correlations is an acceptable tool with reasonable accu... more ABSTRACT Performance prediction by use of correlations is an acceptable tool with reasonable accuracy. However, cumbersome calculations at times make them less popular and difficult to use especially by plant personnel needing quick and easy reckoning. Keeping this in mind, a nomographic approach has been adopted to represent correlation for prediction of liquefied petroleum gas extractor performance. This leads to an easier method of interpretation for faster implementation by process engineers.
... through a septum in the reactor and were analyzed by potentiometric titration method UOP: 163... more ... through a septum in the reactor and were analyzed by potentiometric titration method UOP: 163-89 using a Metrohm Titration Unit (702 SM Titrino, Metrohm AG; Switzerland). ... Elements of Chemical Reaction Engineering New Delhi: Prentice Hall of India Private Limited.. ...
ABSTRACT Liquefied petroleum gas (LPG) demercaptanization by caustic is a widely used process. Th... more ABSTRACT Liquefied petroleum gas (LPG) demercaptanization by caustic is a widely used process. The basic data for its optimization are not present in the literature, however, recently published performance data of an Iranian refinery filled this gap to some extent. It was helpful in developing semi empirical correlations in our previous work, for quickly predicting mercaptans in the product LPG, using process variables, with reasonable accuracy. The authors carried out simulations based on these correlations to optimize LPG extractor performance by fine tuning process parameters, such as solvent to feed mass flow rate ratio, caustic concentration, and temperature, thereby ensuring optimal loading in downstream oxidizer for better kinetics and thus minimizing the overall operating cost of the LPG treatment unit.
This paper reports experimental data on the removal of phenol from aqueous solutions using emulsi... more This paper reports experimental data on the removal of phenol from aqueous solutions using emulsion liquid membranes in a microporous hollow-fiber extractor. The hollow-fiber extractor appears to offer significant advantages over conventional liquid-liquid contactors for this separation because emulsion leakage and swell are practically eliminated even when treating high phenolic feeds. The overall mass-transfer coefficients are seen to be more strongly dependent on the phase flow rates among the parameters studied. The experimental mass-transfer coefficients have been predicted by a resistance-in-series model.
The Indian Auto Fuel Policy aims at limiting sulfur in diesel to 50 ppm by 2010 in selected citie... more The Indian Auto Fuel Policy aims at limiting sulfur in diesel to 50 ppm by 2010 in selected cities. The Ultra Deep Hydrodesulfurisation (UDHDS) catalyst was developed to meet this objective. The performance of this catalyst compares well with a commercial reference catalyst. This study focused on UDHDS kinetic studies using straight run gas oil (SRGO) as a feedstock. Data analysis shows that UDHDS follows second-order kinetics with an effective activation energy of 26.75 kcal/mol. A rate law was proposed based on the estimated kinetic parameters which should be useful for scale-up of a UDHDS process.
In the present study the kinetics of liquid phase oxidation of light thiols using novel cobalt ph... more In the present study the kinetics of liquid phase oxidation of light thiols using novel cobalt phthalocyanine sulphonamide catalyst developed indigenously was investigated in a semi batch reactor. 1-Butanethiol was chosen to represent thiols in lighter range of petroleum fractions like liquefied petroleum gas and light straight run naphtha. Rate data was collected under experimental conditions representing industrial conditions. Effects of process parameters like catalyst concentration and initial feed mercaptan concentration on reaction rates were investigated. A mechanism based rate expression was deduced to explain the observed behavior. Its parameters estimated using Line weaver plots and further fine tuned by using optimization technique. The effective rate law represented a first order kinetics which explained the observed experimental phenomenon reasonably well for commonly encountered industrial conditions.
ABSTRACT Thiols in liquefied petroleum gas are undesirable due to their foul odor and corrosive n... more ABSTRACT Thiols in liquefied petroleum gas are undesirable due to their foul odor and corrosive nature. The process of removing these thiols is termed as sweetening. Metal phthalocyanines are reported to be the most effective sweetening catalyst. However, the solubility of metal phthalocyanine is low in aqueous medium. Thus, in an effort to further improve upon the existing catalysts, a novel cobalt phthalocyanine sulfonamide catalyst was developed. Laboratory and commercial evaluation of this catalyst showed enhanced activity as compared to a commercial catalyst with comparable stability. With proven higher activity, comparable stability, design of grass root oxidizer using this catalyst is the next step. Design of oxidizers for an extractive sweetening process based on this catalyst in grass root refineries requires a rigorous kinetic model. The paper reviews the literature on sweetening kinetics and focuses on the concepts of design of laboratory reactors for reaction kinetics studies for such gas-liquid reactions. Laboratory reactor systems can be useful for accurate estimation of kinetic parameters which can then be used to design industrial reactors and predict their performance.
Magnetically separable layered double hydroxide MgAl–LDH@Fe 3 O 4 composite supported cobalt phth... more Magnetically separable layered double hydroxide MgAl–LDH@Fe 3 O 4 composite supported cobalt phthalocyanine catalyst was synthesized and used for the aerobic oxidation of mercaptans to corresponding disulfides under alkali free conditions. The catalyst exhibited excellent activity for the oxidation of mercaptans using molecular oxygen as an oxidant which can be effectively recovered by using an external magnetic field. In addition, the covalent immobilization of cobalt phthalocyanine to MgAl–LDH@Fe 3 O 4 support prevents the leaching of the catalyst and improves its activity and stability.
Tune up the 'sweetening' process for your facility Novel catalysts can improve the oxidation of t... more Tune up the 'sweetening' process for your facility Novel catalysts can improve the oxidation of thiols (RSH) found in light oils. Thiols in petroleum products, such as liquefied petroleum gas (LPG) and light straight-run naphtha (LSRN), usually found as light RSH compounds. They are undesirable, have a foul odor, and are highly corrosive. Light RSH can also affect the activity of catalysts for downstream processes. The process for removing thiols is referred to as "sweetening. " The thiols are catalytic oxidized to less deleterious disulfides. 1 The light RSH is first extracted with an aqueous caustic solution to form mercaptides, as shown in Eq. 1. The subsequent salts (NaSR) are oxidized in the presence of a catalyst and air to organic disulfides (RSSR) as shown by Eq. 2. The overall reaction can be represented as:
Hydrodesulfurization (HDS) of straight-run naphtha (SRN) reformer feed significantly improves ref... more Hydrodesulfurization (HDS) of straight-run naphtha (SRN) reformer feed significantly improves reformer catalyst life, gasoline yield, and its stability. HDS of SRN helps in protecting the expensive platinum-based reforming catalyst. HDS is usually catalyzed by sulphided Co-Mo/Al 2 O 3 or sometimes Ni-Mo/Al 2 O 3. The design of naphtha HDS units requires the development develop a kinetic model. It is well-known that among the sulphur types present in naphtha, the most persistent sulphur compound is thiophene. Therefore, the design of naphtha HDS units is governed by thiophene HDS rates. It is essential to have experimental conditions free from intraparticle diffusional limitations in order to obtain intrinsic kinetics data. This Communication discusses the calculation procedures involved in ensuring experimental conditions free from pore diffusional resistances before conducting detailed kinetics studies. The pore diffusional resistance was quantified in terms of Thiele modulus (F).
ABSTRACT Novel magnetic silica beads functionalized cobalt phthalocyanine catalyst was prepared b... more ABSTRACT Novel magnetic silica beads functionalized cobalt phthalocyanine catalyst was prepared by immobilization of the sulfonated Co(II) phthalocyanine (CoPcS) on the amino functionalized silica coated magnetic nanoparticles (Fe3O4@SiO2, SMNP) via a sulfonamide linkage. The developed catalyst was characterized by various techniques such as XRD, N2 adsorption-desorption, UV-Vis, FTIR, SEM and TGA analyses. The synthesized catalyst was found to be effective in oxidation of mercaptans in an aqueous medium by using molecular oxygen as oxidant under alkali free conditions. The efficient recovery by using an external magnet along with reusability of the catalyst in an alkali free reaction condition makes this methodology a facile, clean, effective and economically feasible approach for the oxidation of mercaptans to disulfides.
In order to meet environmental norms, Indian fuel policy aims at producing ultra low sulphur dies... more In order to meet environmental norms, Indian fuel policy aims at producing ultra low sulphur diesel (ULSD) in near future. A catalyst for meeting such requirements has been developed and kinetics of this catalytic process is being looked into. In the present investigations, effect of mass transfer on kinetics of ultra deep hydrodesulphurization (UDHDS) to produce ULSD has been studied to determine intrinsic kinetics over a pre-sulphided catalyst. Experiments have been carried out in a continuous flow micro reactor operated in the temperature range of 330 to 360 0 C, whsv of 1 hr -1 at a pressure of 35 bar, and its parameters estimated. Based on the derived rate expression and estimated parameters optimum operation range has been determined for this UDHDS catalyst to obtain ULSD product.
ABSTRACT Performance prediction by use of correlations is an acceptable tool with reasonable accu... more ABSTRACT Performance prediction by use of correlations is an acceptable tool with reasonable accuracy. However, cumbersome calculations at times make them less popular and difficult to use especially by plant personnel needing quick and easy reckoning. Keeping this in mind, a nomographic approach has been adopted to represent correlation for prediction of liquefied petroleum gas extractor performance. This leads to an easier method of interpretation for faster implementation by process engineers.
... through a septum in the reactor and were analyzed by potentiometric titration method UOP: 163... more ... through a septum in the reactor and were analyzed by potentiometric titration method UOP: 163-89 using a Metrohm Titration Unit (702 SM Titrino, Metrohm AG; Switzerland). ... Elements of Chemical Reaction Engineering New Delhi: Prentice Hall of India Private Limited.. ...
ABSTRACT Liquefied petroleum gas (LPG) demercaptanization by caustic is a widely used process. Th... more ABSTRACT Liquefied petroleum gas (LPG) demercaptanization by caustic is a widely used process. The basic data for its optimization are not present in the literature, however, recently published performance data of an Iranian refinery filled this gap to some extent. It was helpful in developing semi empirical correlations in our previous work, for quickly predicting mercaptans in the product LPG, using process variables, with reasonable accuracy. The authors carried out simulations based on these correlations to optimize LPG extractor performance by fine tuning process parameters, such as solvent to feed mass flow rate ratio, caustic concentration, and temperature, thereby ensuring optimal loading in downstream oxidizer for better kinetics and thus minimizing the overall operating cost of the LPG treatment unit.
This paper reports experimental data on the removal of phenol from aqueous solutions using emulsi... more This paper reports experimental data on the removal of phenol from aqueous solutions using emulsion liquid membranes in a microporous hollow-fiber extractor. The hollow-fiber extractor appears to offer significant advantages over conventional liquid-liquid contactors for this separation because emulsion leakage and swell are practically eliminated even when treating high phenolic feeds. The overall mass-transfer coefficients are seen to be more strongly dependent on the phase flow rates among the parameters studied. The experimental mass-transfer coefficients have been predicted by a resistance-in-series model.
The Indian Auto Fuel Policy aims at limiting sulfur in diesel to 50 ppm by 2010 in selected citie... more The Indian Auto Fuel Policy aims at limiting sulfur in diesel to 50 ppm by 2010 in selected cities. The Ultra Deep Hydrodesulfurisation (UDHDS) catalyst was developed to meet this objective. The performance of this catalyst compares well with a commercial reference catalyst. This study focused on UDHDS kinetic studies using straight run gas oil (SRGO) as a feedstock. Data analysis shows that UDHDS follows second-order kinetics with an effective activation energy of 26.75 kcal/mol. A rate law was proposed based on the estimated kinetic parameters which should be useful for scale-up of a UDHDS process.
In the present study the kinetics of liquid phase oxidation of light thiols using novel cobalt ph... more In the present study the kinetics of liquid phase oxidation of light thiols using novel cobalt phthalocyanine sulphonamide catalyst developed indigenously was investigated in a semi batch reactor. 1-Butanethiol was chosen to represent thiols in lighter range of petroleum fractions like liquefied petroleum gas and light straight run naphtha. Rate data was collected under experimental conditions representing industrial conditions. Effects of process parameters like catalyst concentration and initial feed mercaptan concentration on reaction rates were investigated. A mechanism based rate expression was deduced to explain the observed behavior. Its parameters estimated using Line weaver plots and further fine tuned by using optimization technique. The effective rate law represented a first order kinetics which explained the observed experimental phenomenon reasonably well for commonly encountered industrial conditions.
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