Ethane Conversion Research Articles

Investigation of catalytic reaction of ethylene dimerization to butene-1 by use of DCPDS as a modifier based on response surface methodology

Butene-1 is one of the most important petrochemical industry products that is produced in different ways. Ethylene is an important source of Butene-1 production through the oligomerization process. In this study, to reduce the by-product of the polymer produced and to improve the catalyst yield, the dicyclopentyldimethoxysilane (DCPDS) modifier in the presence of a homogeneous titanium tetra butoxide/triethyl aluminum catalyst and a combination of dichloromethane (as a promoter) in a high-pressure Buchi reactor were used. Gas chromatography was used for liquid and gas phase analysis in the reactor. The design of experiments was performed with the Box-Behnken design technique (BBD) based on the response surface method (RSM). In this method, four effective factors of catalyst concentration, modifier, promoter, and temperature were evaluated. The results of the analysis of variance for the answers of ethylene conversion rate, selectivity, polymer production rate, and yield showed that there is a good agreement between the actual values and the values obtained from the model. Optimization using design expert software showed values of 85.6, 88.5, 2.43, and 75.78% for ethylene conversion rate, selectivity, polymer content and yield, respectively, which showed an error of less than one percent compared to the laboratory results. Comparison of the catalyst performance with and without DCPDS and DCM showed that the presence of these two compounds together with the catalyst, in addition to increasing by 4, 6, and 9% for conversion, selectivity of Butene-1 and yield, respectively, reduced the production of the undesirable polymer in the reactor from 136 mg to 2.4 mg.

Impact of Acidity and Metal Particle Size on the Competitive Pathways of Benzyl Phenyl Ether Conversion to Aromatics and Cycloalkanes in a Nonpolar Solvent

Impact of Acidity and Metal Particle Size on the Competitive Pathways of Benzyl Phenyl Ether Conversion to Aromatics and Cycloalkanes in a Nonpolar Solvent

Investigation of optimal operating conditions in dimethyl ether carbonylation to methyl acetate production process.

Ethanol production methods are expanding due to the importance of ethanol as a fuel or additive to fuels. One of these methods is converting methanol to ethanol in a three-step process. All of these steps need to deeply study and investigate to develop the process. In this research, the carbonylation of dimethyl ether to produce methyl acetate, which is the intermediate reaction of the three-step process of methanol to ethanol, has been simulated and optimized. The parameters of temperature, pressure, residence time, and feed ratio have been investigated as effective operational parameters of the process. It has been shown that the temperature and pressure of the process are more effective in the ranges of 220-280 °C and 30-50 bar, respectively. The simulation results showed a maximum point in dimethyl ether conversion in the feed ratio of 0.4-0.6, i.e., in temperature of 260 °C, residence time of 5 h, pressure of 45 bar, DME/CO/Ar = 30/67/3, and DME conversion about 22%. Also, it has been shown that increasing the residence time increases the effect of each of the above parameters. Optimization of the dimethyl ether carbonylation process has demonstrated that the combination of different ranges of the above parameters achieves the desired conversion, i.e., in pressure of 48.23 bar, temperature of 259.06 °C, residence time of 3.68 h, and dimethyl ether/feed of 0.461 vol%; conversion of dimethyl ether will be equal to 85.50%.

Design and optimization of hydrogen production system model for dimethyl ether self-heating steam reforming

Hydrogen, as a clean energy source, has been widely used in the automotive industry. However, considering the difficulties of hydrogen storage and transportation, the in-situ production process has received increasing attention. In this paper, a hydrogen production system for dimethyl ether self-heating steam reforming is proposed, using a spiral tube reactor in which the oxidation of dimethyl ether occurs in the spiral tube, and the exothermic oxidation of dimethyl ether is used to provide heat for the dimethyl ether steam reforming hydrogen production reaction. A numerical model of the hydrogen production system for dimethyl ether self-heating reforming is developed, the model is simulated and analyzed, the accuracy of the model is verified through experiments, the influence of various parameters and on the system is analyzed, and the system is optimized. The results show that the proposed system can solve the problems of high energy consumption, low hydrogen yield and difficult reaction control faced by traditional autothermal reforming hydrogen production, and the system can achieve 87.79% dimethyl ether conversion rate, 84.94% hydrogen yield and 85.94% system thermal efficiency.

Ru nanoparticles supported on various metal-modified (La, Zr, Cr, Ce and Ga) α-Al2O3 for the selective hydrogenolysis of lignin and its derived ethers

Controlling the C-O bond hydrogenolysis while suppressing the direct hydrogenation of aromatic rings in lignin-derived ethers is critical and challenging for the utilization of lignin. Herein, a series of metal-modified (La, Zr, Cr, Ce and Ga) α-Al2O3-supported Ru-based catalysts were synthesized for the conversion of diphenyl ether (DPE). The catalyst characterizations demonstrate that the metal modification cannot change the chemical valence of Ru but promotes the dispersion of Ru nanoparticles and adjusts the adsorption state of DPE. The results indicate that the metal modification inhibits the arenes hydrogenation at low temperatures but facilitates the C-O bond cleavage during heating (at low H2 pressures or an inert atmosphere). Ru-Cr/α-Al2O3 shows the highest reaction rate for DPE conversion at 1 MPa Ar and 200 °C. Moreover, Ru-Cr/α-Al2O3 not only efficiently converts different lignin model compounds by hydrogenolysis, but also achieves the controlled depolymerization of real lignin to generate guaiacols under mild conditions.

Role of active oxygen species in Fe-doped ZrO2 catalyst during CO2 assisted ethane dehydrogenation reaction

CO2 assisted ethane dehydrogenation provides a promising route for the utilization of shale gas and greenhouse gas. This study investigates the role and evolution of active oxygen species over Fe-doped ZrO2 catalysts in distinct dehydrogenation reactions via Mars-van Krevelen mechanism. Fe doping led to an increase in active oxygen species (from 12.9% to 23.4%) benefitted from the phase transformation of ZrO2. This enhancement significantly boosted ethane dehydrogenation activity from 5.0 to 16.1 mmolEthene/gCat/h. In the absence of CO2, the ethane conversions rapidly decreased with a deactivation rate constant (kd) of 0.930 h−1 due to the irreversible oxygen species loss and coke deposition. Although the catalytic stability of the optimal catalyst was greatly improved (kd = 0.006 h−1) after CO2 introduction, a decrease in ethane conversion occurred when CO2 could not supplement oxygen species due to the formation of coke layers. A simple O2 oxidation can effectively restore stable activity during 5 reaction-regeneration cycles for 3600 mins.

Stable and selective conversion of ethylene to propylene and butylene using Ni-loaded dealuminated Beta zeolite catalyst

The selective conversion of ethylene into propylene (ETP) has garnered significant attention due to the growing demand for the product of this reaction in the petrochemical industry. In this study, we developed a series of Ni-loaded dealuminated Beta zeolite catalysts for the ETP reaction. The catalyst loaded with 0.07 wt% Ni showed stable and high catalytic activity with 28% propylene yield and 16% butylene yield, despite very low Ni content compared to previously reported catalysts. Temperature-programmed H2 reduction and NH3-desorption analyses showed that the active sites were Ni species grafted onto the defective silanols of dealuminated zeolites.

Modeling and Simulation of a Multizone Circulating Reactor for Polyethylene Production with Internal Cooling.

Polyolefins play a role in industries and are typically manufactured using two types of reactors: high-pressure tubular reactors and fluidized bed reactors. An innovative technology called the Multizone Circulating reactor (MZCR) has emerged, which introduces an innovative approach with interconnected polymerization zones creating a continuous loop of polymer flow. This study focuses on modeling and simulating ethylene gas phase polymerization within the MZCR in the presence of internal cooling to gain insights into its behavior. To achieve this, a comprehensive computational fluid dynamics (CFD) simulation was developed. It considered momentum, material, and energy balance aspects. The model equations were solved using the finite difference method in COMSOL Multiphysics version 6.1. The investigation primarily focused on studying the impact of incorporating a cooler into the riser section on the temperature profile within the reactor and ethylene conversion. The presence of this cooler resulted in a reduction in temperature change along the riser from approximately 8.0 °C to 4.0 °C. Moreover, it led to an increase of 7%, in ethylene single-pass conversion.

Ethylene photocatalytic degradation using TiO2 immobilized in a NETmix mili-photoreactor

Ethylene oxidation by TiO2 photocatalysis was studied in a mili-photoreactor (NETmix), as a potential clean postharvest technology to scavenge ethylene from fruit. The NETmix photoreactor comprises a stainless steel slab imprinted with a network of cylindrical chambers interconnected by prismatic channels, sealed by a UVA transparent borosilicate slab (BS), and a UVA LED plate paced above the reactor window. A thin film of the photocatalyst was immobilized in the NETmix network or on the side of the borosilicate slab in contact with the ethylene gas stream. Ethylene oxidation in single-pass mode (continuous operation) was evaluated as a function of TiO2 crystallinity, TiO2 loading, radiant power, illumination mechanism, feed stream composition (ethylene and water concentration), and flow rate. The catalyst loading and deposition surface, and relative humidity (RH) of the feed stream strongly affected the ethylene conversion, mineralization, and reaction rate. Even under severe conditions (RH = 25% and Qfeed = 571 cm3 min−1 for the back side illumination), the NETmix removed at least 0.11 μmolethylene min−1. The high efficiency of the photocatalytic NETmix reactor allows the removal of ethylene from the storage system at the beginning of fruit ripening, the period of the highest gas production, enabling it to be used as a promising technology in controlling fruit ripening.

Regulating ethane and ethylene synthesis by proton corridor microenvironment for CO2 electrolysis

Electrocatalytic reduction of carbon dioxide is one of the most effective strategies to achieve carbon neutrality and energy sustainability. Although high-value multi-carbon products have been widely studied, limited electrocatalysts have been reported for the selective conversion of ethane. More importantly, the factors tuning the selectivity between ethane and ethylene have not been clarified. Here, Zn@Cu nanowire arrays (Zn@Cu-NWAs) catalyst is proposed to stimulate the maintenance of efficient CO2-to-C2H6 conversion at high current densities. Meanwhile, in order to investigate the factors affecting the interconversion between ethane and ethylene, the counterpart catalyst that facilitates C–C coupling to ethylene was also synthesized. Time-of-flight secondary-ion mass spectroscopy (TOF-SIMS), in-situ Raman spectroscopy, and simulation results show that Zn@Cu-NWAs can provide a localized proton corridor environment for the formation of ethane, accelerating the further proton-coupled CO2 reduction reaction (CO2RR) kinetics. Hence, this catalyst delivered an ethane Faraday efficiency of over 65% at −1.14 V vs. RHE with a total current density of 142.3 mA/cm2. This work provides a new perspective on regulating the local microenvironment to modify the selectivity of multi-carbon products.

Assessment of CaO-based sorbent/spinel catalyst composites for the oxidative dehydrogenation of ethane in isothermal integrated CO2 capture and utilization

In this study, a comparative analysis of the isothermal integrated CO2 capture and utilization (ICCU) performance of MgB2O4 (B = Cr, Ga, Fe, Al)/CaCe15 was conducted. Results show that MgCr2O4/CaCe15 demonstrates exceptional performance, with CO2 uptake capacity, CO2 conversion, ethane conversion, ethylene selectivity, and ethylene yield after multiple cycles measuring at 0.22 g/g, 35.6 %, 19.6 %, 89 %, and 17.4 %, respectively. The dominant mechanism during the CO2 utilization stage was explored, and the coupling mechanism of catalytic dehydrogenation and reverse water–gas shift reaction is dominant. The reaction pathway during CO2 utilization was investigated, and results show that hydrogenation activation (CO2*+H* → HCOO* → CO*+OH*) is the primary pathway for CO2 dissociation, with the oxidative dehydrogenation of ethane mainly attributed to the activation of C–H on distinct C atoms, CH3CH3* → CH3CH2* → CH2CH2*. Meanwhile, the scission of the first C–H bond during CO2 utilization is the rate-determining step. Furthermore, we investigated the influencing factors and discovered that increasing the concentration of ethane and weight hourly space velocity both lead to a decrease in ethylene yield.

Photocatalytic Oxidative Coupling of Ethane to n-Butane Using CO2 as a Soft Oxidant over NiTi-Layered Double Hydroxide.

Selective conversion of ethane (C2 H6 ) to high-value-added chemicals is a very important chemical process, yet it remains challenging owing to the difficulty of ethane activation. Here, a NiTi-layered double hydroxide (NiTi-LDH) photocatalyst is reported for oxidative coupling of ethane to n-butane (n-C4 H10 ) by using CO2 as an oxidant. Remarkably, the as-prepared NiTi-LDH exhibits a high selectivity for n-C4 H10 (92.35%) with a production rate of 62.06 µmol g-1 h-1 when the feed gas (CO2 /C2 H6 ) ratio is 2:8. The X-ray absorption fine structure (XAFS) and photoelectron characterizations demonstrate that NiTi-LDH possesses rich vacancies and high electron-hole separation efficiency, which can promote the coupling of C2 H6 to n-C4 H10 . More importantly, density functional theory (DFT) calculations reveal that ethane is first activated on the oxygen vacancies of the catalyst surface, and the C─C coupling pathway is more favorable than the C─H cleavage to C2 H4 or CH4 , resulting in the high production rate and selectivity for n-C4 H10 .

Ruthenium catalysts supported on activated carbon from corncob waste for selective hydrogenolysis of C–O bonds in lignin-derived aromatic compounds

Selective hydrogenolysis of C–O bonds in lignin is regarded as an important process to produce high value-added chemicals and biofuels. Herein, high-performance Ru-based catalysts (Ru/AC) supported on activated carbon (AC) derived from corncob waste were prepared by a simple impregnation method. The optimal 5%Ru/AC possessed enormous specific surface area, well-developed porosity, high metal dispersion, small Ru particle size and strong metal-support interaction, showing a marvelous catalytic performance in the hydrogenolysis of diphenyl ether, benzyl phenyl ether and phenylethyl phenyl ether with different kinds of C–O bonds under mild conditions. Besides, various phenolic compounds were selectively hydrogenated into cycloalkanols and cycloalkanes over 5%Ru/AC, indicating the excellent catalytic activity in aromatic ring hydrogenation of this catalyst. In addition, high conversion of diphenyl ether and high selectivity of monomeric products were well maintained after employing this catalyst at least three times. The construction and application of the ingenious 5%Ru/AC catalyst highlighted a promising approach to the value-added utilization of lignin-derived aromatic compounds.

Diels-Alder conversion of biomass-derived furans and ethylene to renewable aromatics over mesoporous titanium phosphate

Metal phosphates such as P-Beta, Zr-P and Sn-P have drawn lots of attention as emerging catalysts for biomass conversion due to its mild acidity which results in high selectivity to the targeted products while minimizing the unwanted side reactions such as coking that are prevalent in reactive biomass-derived compounds. In this study, we have investigated the production of sustainable aromatics such as p-xylene (PX) and toluene (TOL) via Diels-Alder cycloaddition (DAC) of biomass-derived 2,5-dimethylfuran (DMF) and 2-methylfuran (MF) with ethylene over titanium phosphate catalysts. Specifically, the effects of synthesis method (e.g., sol-gel vs hydrothermal), activation method and P/Ti molar ratio on the structural and acid properties of titanium phosphate catalysts were systematically studied to understand the catalytic consequences of the titanium phosphate materials for the DAC of furans. In addition, amphiphilic surfactant was applied to all catalysts for the formation of mesoporous structure. The characterization studies of the prepared catalysts using XRD, BET, FT-IR, XPS, NMR spectroscopy and TPD of ammonia indicated that the degree of Ti-O-P bond formation, catalysts surface area and surface acidity are largely affected by the catalysts synthesis conditions. Overall, the mesoporous titanium phosphate catalyst, synthesized by hydrothermal method at 180 ℃ for 12 h followed by ethanol refluxing at 60 ℃ for 24 h at a molar P/Ti ratio of 1 showed the highest surface area and the highest acid site density which arise from its distinct ordered Ti-O-P bonding structure as evidenced by XPS and NMR. The catalyst demonstrated the remarkably high PX selectivity of > 90 % at the high DMF conversion of > 90 % and the reusability after two successive reaction-regeneration cycles, showing high phosphorus leaching tolerance.

Synthesis of SSZ-13 zeolites using calcined rice husk as silica source for propylene production from ethylene and carbon dioxide adsorption

A zeolite named SSZ-13, with a small pore of 8-membered rings, is an attractive porous material for DeNOx, CO2 capture/separation, methanol-to-olefin conversion, and direct conversion of ethylene to propylene (DCEP). Although the synthesis of SSZ-13 has been done for a long time and is useful for some applications, further development in the synthesis is required to reduce the production cost or to optimize the preparation. On the other hand, the utilization of waste is important for our sustainability. In this study, SSZ-13 zeolite was synthesized using rice husk-derived silica, for the first time, in order to prepare SSZ-13 at a low cost and utilize agricultural byproducts in zeolite synthesis. Via this research, it was found that SSZ-13s could be synthesized readily by using rice husk-derived silica even without seed crystals. Synthesis at 180 °C for 5–7 d leads to SSZ-13 from the gel with a wide range of silica/alumina ratios. Prepared SSZ-13 in proton form, together with a commercial SSZ-13, was utilized in DCEP and CO2 adsorption at low pressure. The two H-SSZ-13s showed very similar performances in DCEP and CO2 capture, showing an agricultural waste or byproduct, rice husk, can be successfully utilized in the preparation of SSZ-13 zeolites.

Performance of HZSM-5 agglomerated in a mesoporous matrix in the fuel production from ethylene at atmospheric pressure

Ethylene oligomerization into liquid fuels at slightly over atmospheric pressure has been studied due to its interest to valorize online the excess of ethylene in sustainable olefins production processes and to intensify the production of fuel from refinery secondary streams. Runs were carried out in a fixed-bed reactor under the following conditions: 1.5 bar; 275–375 °C; space time, 2.7–16.2 gcatalyst h molC−1; time on stream, 5 h. The catalyst was prepared by agglomerating a HZSM-5 zeolite (SiO2/Al2O3 of 30) in a mesoporous matrix (γ-Al2O3/α-Al2O3). The hierarchical porous structure of the catalyst enables to reach a pseudo-steady state with a remarkable remnant activity after an initial deactivation period of 2–3 h. Temperature shows a relevant effect on ethylene conversion and product distribution, where a C5+ liquid fuel yield of 55% above 325 °C and 10.6 gcatalyst h molC−1 is obtained. At 325 °C, gasoline yield is 60%, with high olefin content (49%), which decreases at higher temperature, due to an increase in aromatic and paraffin concentration. Soft and hard coke analysis reveal the role of the matrix to attenuate deactivation. Moreover, above 325 °C the cracking of hard coke precursors deposited in the zeolite micropores prevails respect to their formation.

One‐pot synthesis of V doped mesoporous SiO2 catalysts for selective oxidation of ethane and propane

AbstractA series of vanadium‐doped mesoporous SiO2 catalysts were prepared using a one‐pot emulsion method. The effects of VOx species with different structures on C−H bond activation and product selectivity in ethane and propane selective oxidation were investigated using X‐ray diffraction (XRD), N2 adsorption‐desorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman, ultraviolet‐visible diffuse reflectance spectroscopy (UV‐Vis DRS), hydrogen temperature programmed reduction (H2‐TPR), and ammonia temperature programmed desorption (NH3‐TPD) characterizations. The results revealed that the highly dispersed isolated tetrahedral VOx species on the catalyst gradually polymerized into highly dispersed oligomeric VOx species with the increased V loading. The former is beneficial for the formation of olefins and total aldehydes during the selective oxidation of propane. Oligomeric VOx species are conducive to improving the selectivity of ethylene and acetaldehyde in the selective oxidation of ethane. The highest catalytic performances for selective oxidation of ethane and propane were obtained at a temperature of 650 °C. The conversion of ethane was 41.6 %, with a corresponding yield of ethylene and acetaldehyde of 23.6 % over a 0.5 V−SiO2 catalyst. In contrast, the propane conversion was 61.5 %, with a corresponding total yield of olefins and aldehydes of 41.3 % over a 1.0 V−SiO2 catalyst.

The Superiority of TiO2 Supported on Nickel Foam over Ni-Doped TiO2 in the Photothermal Decomposition of Acetaldehyde.

Acetaldehyde decomposition was performed under heating at a temperature range of 25-125 °C and UV irradiation on TiO2 doped by metallic Ni powder and TiO2 supported on nickel foam. The process was carried out in a high-temperature reaction chamber, "The Praying MantisTM", with simultaneous in situ FTIR measurements and UV irradiation. Ni powder was added to TiO2 in the quantity of 0.5 to 5.0 wt%. The photothermal measurements of acetaldehyde decomposition indicated that the highest yield of acetaldehyde conversion on TiO2 and UV irradiation was obtained at 75 °C. The doping of nickel to TiO2 did not increase its photocatalytic activity. Contrary to that, the application of nickel foam as a support for TiO2 appeared to be highly advantageous because it increased the decomposition of acetaldehyde from 31 to 52% at 25 °C, and then to 85% at 100 °C in comparison with TiO2 itself. At the same time, the mineralization of acetaldehyde to CO2 doubled in the presence of nickel foam. However, oxidized nickel foam used as support for TiO2 was detrimental. Most likely, different mechanisms of electron transfer between Ni-TiO2 and NiO-TiO2 occurred. The application of nickel foam greatly enhanced the separation of free carriers in TiO2. As a consequence, high yields from the photocatalytic reactions were obtained.

Catalytic Performances of Co/TiO2 Catalysts in the Oxidative Dehydrogenation of Ethane to Ethylene: Effect of CoTiO3 and Co2TiO4 Phase Formation

Co/TiO2 catalysts with different cobalt loadings (3.8, 7.5 and 15 wt%) were prepared by impregnation method of Co(NO3)2 6H2O over titania. Samples containing Co(NO3)2·6H2O and TiO2 in stoichiometric proportions in order to obtain CoTiO3 and Co2 TiO4 phases were also synthesized. The effect of the calcination treatment at two different temperatures, 550 and 1150 °C, was investigated. Characterizations by several techniques, such as XRD, UV–vis–NIR, DRS, Raman and XPS, were carried out. XRD showed the coexistence of three phases: CoTiO3; Co2TiO4 and Co3O4 after calcination at 550 °C, while calcination at high temperature (1150 °C) led to single-phase systems (CoTiO3 or Co2TiO4). Diffuse reflection and XPS spectroscopy showed that divalent cobalt occupies octahedral sites in the ilmenite phase, and both tetrahedral and octahedral sites in the spinel phase. The catalytic performances of the prepared catalysts were evaluated in the oxidative dehydrogenation reaction (ODH) of ethane to ethylene, as a function of the Co content for Co/TiO2 catalysts and as a function of the calcination temperatures for the CoTiO3 and Co2TiO4 phases. Co(7.5)/TiO2 was the most active, although the conversion of ethane decreased in the first 150 min of the reaction, reaching values comparable to those of Co2TiO4 and CoTiO3; however, Co(7.5)/TiO2 was confirmed as having the best selectivity to ethylene in comparison with the bulk phases, CoTiO3 and Co2TiO4. The influence of the reaction mixture composition, specifically the presence of water, at different percentages, was investigated. There is a decrease in the overall ethane conversion and an increase in the ethylene selectivity when the percentage of water increases. This behavior can likely be attributed to an increase in the surface concentration of hydroxyl species (OH), resulting in heightened surface acidity.

Oxidative and Nonoxidative Conversion of Ethylene in Dielectric Barrier Discharge

The oxidative and nonoxidative conversion of ethylene in a dielectric barrier discharge in the presence of water with the formation of predominantly unsaturated compounds (acetylene, butene, butadiene) has been studied. The efficiency of ethylene conversion in argon is shown in comparison with its oxidation by air into oxygenates. A simple theoretical estimate of the energy loss of discharge electrons in the feed gas mixture and simple kinetic calculations make it possible to explain both the change in the degree of ethylene conversion and the direction of the process