Ion-exchanged Catalysts Research Articles

Tolerance of Cu-SSZ-13 catalysts to potassium sulfate: Strong Brønsted acid sites and copper species

Potassium sulfate is one of the most important impurities deposited on the NH3-SCR catalysts from alkali-rich gas exhausts. In this work, two Cu-SSZ-13 catalysts synthesized by one-pot and ion-exchange methods were compared for their tolerance to potassium sulfate. The evolutions of copper species and acid sites, as the critical mechanisms of K2SO4 poisoning, were revealed by comprehensive characterizations. It was found that Si-O(H)-Al sites act as sacrificing sites upon K+ attacking to preserve Cu2+ ions as active sites. ZCuOH sites are preferentially detached by K+ ion-exchange and trapped predominantly by the surface sulfate anions as inactive Cu2OSO4. Therefore, the one-pot Cu-SSZ-13, with abundant acid sites and high Z2Cu proportion, shows superior K2SO4 resistance than the ion-exchanged catalyst.

Application of a Loop Reactor in the Investigation of Furfural Oxidation Kinetics on an Acidic Ion Exchange Catalyst

Application of a Loop Reactor in the Investigation of Furfural Oxidation Kinetics on an Acidic Ion Exchange Catalyst

3D Stochastic Network Modeling and Investigation of Network Size Effect on the Porous Media Structure of Ion Exchange Catalyst Amberlyst-35 with Computer Programs

In the present paper, the investigation was focused on the physical characterization and determination of porosity for an ion exchange catalyst called Amberlyst-35, which produces environmentally benign gasoline using 3D network modeling (3DNM). In addition, the effect of the different pore size distributions (PSD) has been investigated in porous media (PM). First, the mercury porosimetry (MPo) experiment was carried out to determine the porosity of the Amberlyst-35. Second, the KALINET program was run by Compact Visual Fortran (CVF) and Graphical Input/Output (GINO) for modeling porous structures. Then, the SECTION program was used for different porous 3D random images. The theoretical penetration curve was drawn using data obtained from the KALINET program and fitted to the experimental penetration values of Amberlyst-35 by changing the number of pores in each pressure interval of the PSD. The PSD was a 3D network model size of (N) = 30x30x30, 40x40x40, 50x50x50, which included 83,700-196,800-382,500 pores, respectively. On the other hand, various sections of the 3D stochastic images of the pore network were obtained from the SECTION program. Finally, 3D network images were drawn by the KALINET3D computer program. The MPo method has been applied using computer programs (with desktop computers). Moreover, it was found that the same results were obtained for both the theoretical and experimental data of MPo.

Recent Progress in Electrocatalytic Conversion of CO2 to Valuable C2 Products

AbstractConverting CO2 into high value‐added chemicals by renewable energy directly alleviates the problem of resource shortages, while also reduces the amount of CO2 in the atmosphere. Among various CO2 reduction methods, CO2 electroreduction has attracted much attention because of its moderate operating conditions and a green and easy‐to‐scale strategy. In this work, the four catalyst enhancement mechanisms: synergistic effect, strain effect, ligand effect, and defect effect are briefly described. Then, the catalytic mechanisms of the C2 products are fully expounded, depending on the number of transferred electrons during the CO2 reduction process. In addition, the membrane electrode is also introduced from the three aspects of ion exchange membrane, catalyst layer, and gas diffusion layer. Finally, the developing direction of CO2 reduction reaction is proposed. This work provides an essential guide for design and preparation of CO2 electroreduction catalysts and fully summarized the intrinsic catalysis mechanism, which is beneficial to the development of CO2 conversion in the future.

Synthesis of Ion-Exchange Catalysts by Introduction of Fluorinated Ponytails into Novel Mesoporous Polymers.

A novel synthetic procedure for the functionalisation of styrenic cross-linked polymers with perfluorinated acyl chains has been reported. The effective significant grafting of the fluorinated moieties is supported by {1H}-13C and {19F}-13C NMR characterisations. This kind of polymer appears promising as catalytic support for a variety of reactions requiring a highly lipophilic catalyst. Indeed, the improved lipophilicity of the materials resulted in enhanced catalytic properties of the corresponding sulfonic materials in the reaction of esterification of a solution in a vegetable oil of stearic acid with methanol.

Controlling Nanosheet Spacing of ZnAl-Layered Double Hydroxide Assemblages for High-Efficiency Hydrogenation of CO2 to Methanol

Three different morphological variations of monodispersed Zn-Al-containing layered double hydroxide (ZnAl-LDH) microspheres were synthesized, with varying degrees of spacing between the nanosheets. The ZnAl-LDH materials were calcined into Zn-Al-containing layered double oxide (ZnAl-LDO) microspheres and loaded with Cu to be used as catalyst candidates for CO2 hydrogenation to methanol under high pressure and constant flow. Two different low-cost facile Cu loading methods were also employed, namely, wet impregnation and ion exchange. The different morphological variations were then evaluated and compared by computational fluid dynamics (CFD) simulation (ANSYS Fluent) as well as the hydrogenation reaction of CO2 to methanol with the purpose of exploring the effect of nanosheet spacing on catalyst performance in terms of the overall catalytic activity and methanol selectivity. The different metal loading methods have also led to different stability results, where there is a slight drop in performance of the incipient wet-impregnated catalyst, while the ion-exchanged catalyst retains much better performance over the same period of 40 h. Based on our simple CFD modeling, an increase in the nanosheet spacing improves convection-driven vortices within the wider channels of the LDH assemblage, with the vortices reaching deeper into the interior core of the microsphere. The simulated vortex phenomena explain the higher catalytic activities observed in our experimental results. This work indicates that catalysts with intricate morphological structure engineering would significantly enhance their catalytic activities.

Application of Lignosulfonates to Reduce Waste of Spent Ion-exchange Catalysts in Petrochemical Production

The paper considers ways to reduce industrial waste of spent cation exchange catalysts by pre-purification of hydrocarbon raw materials from catalytic poisons with lignosulfonates. The indicators for evaluating the effectiveness of lignosulfonates are highlighted, the normalized values for ensuring the quality of purification are indicated. To achieve the results of purification, optimal conditions for the preparation of primary lignosulfonate compounds are shown. Taking into account the duration of decomposition of waste cation exchange catalysts, the efficiency of large-scale implementation of the results obtained is evaluated, ways of significantly increasing the duration of operation of ion exchange catalysts are indicated. Catalytic poisons are captured by biodegradable lignosulfonate, which can be reused as components of drilling fluids or regenerated for re-filtration from catalytic poisons.

Hydrodesulfurization of 4,6-Dimethyldibenzothiophene and the Diesel Oil Fraction on NiMo Catalysts Supported over Proton-Exchanged AlMCM-41 and TiMCM-41 Extrudates

NiMo catalysts supported on mesoporous MCM-41 type materials shaped with binder were tested for activity in the hydrodesulfurization of 4,6-dimethyldibenzothiophene (4,6-DMDBT) and the diesel fuel fraction (0.92 wt% of sulfur). The aim of the investigation was to evaluate the effect of ion exchange with protons of Al- or Ti-substituted MCM-41 mesoporous supports. The subjected catalytic systems were NiMo/HAlMCM-41 and NiMo/HTiMCM-41, and for comparison purposes NiMo/AlMCM-41 and NiMo/TiMCM-41. The samples were characterized by N2 sorption (at 77 K), XRD, TEM, XPS, SEM and Py–IR. It was found that the functionalization of AlMCM-41 and TiMCM-41 with protons increased the conversion of 4,6-DMDBT and the pseudo-first-order rate constant. Correspondingly, 4,6-DMDBT HDS reactions over the NiMo/HTiMCM-41 catalyst proceeded to a similar extent via hydrogenation and direct desulfurization, whereas over the NiMo/HAlMCM-41 they proceeded mainly via direct desulfurization. Furthermore, the ion-exchanged catalysts displayed two-fold higher efficiency in direct desulfurization than their non-modified counterparts. The NiMo/HTiMCM-41 catalyst exhibited the highest catalytic efficiency in the HDS of 4,6-DMDBT and the diesel oil fraction. The high activity of the NiMo/HTiMCM-41 catalyst is mainly attributed to its appropriate acidity, as well as the metal–support interaction providing both the high dispersion of the active phase and the desirable multilayered stacking morphology of the active phase slabs.

Kinetic Model Based on Eley-Rideal and Irreversible Mechanism for Multilevel Reaction of Biodiesel Synthesis

As a new technology, an ion exchange catalyst as a heterogeneous catalyst became a good potential in exchanging the homogeneous base. A kinetic model based on Eley-Rideal mechanism and irreversible multiple reaction of biodiesel synthesis by using heterogeneous catalyst has been simulated in this work. The aim of this study is to obtain the kinetic parameter value of biodiesel synthesis with ion exchange heterogeneous catalyst. In addition, a sensitivity analysis was also studied to evaluate the effect of kinetic parameter value against the change in concentration profile of biodiesel synthesis. A kinetic model data used in this study was obtained from different experiment literatures. Based on the kinetic model of Eley-Rideal mechanism, the results of reaction rate constant values (k1-k6) were 7.87×10−3, 8.75×10−7, 1.1×10−2, 1.12×10−6, 9.14×10−3 and 5.09×10−4, respectively. In addition, for irreversible kinetic simulation, the most accurate value was showed that 1.5 mol/l of fatty acid at initial reaction has been changed after 180 minutes reaction into 1.5×10−4 mol/l of trygliceride, 2.25×10−4 mol/l of diglyceride, 2.4×102 mol/l of monoglyceride and 1.453 mol/l of biodiesel yield. The obtained values of irreversible kinetic parameter (k1-k3) were 7.86×10−3, 1.11×10−2 and 9.15×10−3, respectively.

Optimization of solvent free ohmic-assisted heating as a promising esterification tool for ethyl butyrate synthesis

Solvent free ohmic-assisted esterification (OAE) was investigated as a promising tool for ethyl butyrate (pineapple flavor) synthesis. To this end, Amberlyst 15 dry was used as an ion exchange catalyst to promote the esterification reaction between ethanol and butyric acid. Solubility, electrical conductivity, and heating rate of the reaction mixture as affected by different salt types and concentrations were studied. Then, the OAE operation parameters (i.e., electrical field, catalyst concentration, and mole ratio of ethanol:butyric acid) were optimized. The highest ethyl butyrate yield (63%) was achieved after 90 min in presence of 1% LiCl, 2% Amberlyst 15 dry using field strength of 25 V/cm and an ethanol:butyric acid mole ratio of 1:1. Optimum conditions of OAE were also compared with microwave- and magnetic stirrer-assisted esterification methods. OAE provided the highest yield (61.20%) at a shorter time with the lowest specific energy consumption (0.04 kWh/g ethyl butyrate) and specific CO2 emission (0.03 kg CO2/g ethyl butyrate). The micrographs of scanning electron microscopy showed less structural damages in the catalyst structure using OAE compared to other esterification methods. Therefore, OAE can be proposed as a cost-effective and environmentally friendly technology for the synthesis of flavor esters in the food industry.

Synthesis of Co/Mesoporous Silica-Alumina Catalyst from Sidoarjo Mud Templated by Bovine Bone's Gelatin for Hydrocracking of Waste Lubricant

The synthesis of Co/Mesoporous Silica-Alumina (MSA) catalyst from Sidoarjo mud templated by bovine bone’s gelatin for hydrocracking of waste lubricant has been done. The gelatin was obtained from bovine bone by the combination method of acids (CH 3 COOH 4% and HCl 1 M) and base (NaOH 0.1 M). The silica was obtained from Sidoarjo mud using the batch method (distilled water, HCl 6 M, and NaOH 6 M). The synthesis of MSA was carried out using silica from Sidoarjo mud with the variation of Si/Al of 25, 50, and 100, respectively, using gelatin as a template to produce MSA(25), MSA(50), and MSA(100); and was then analyzed by FTIR and acidity test. The MSA with the highest acidity and optimum thermal stability (MSA(x)) was analyzed by GSA and TEM. The cobalt metal from Co(NO 3 ) 2 ·6H 2 O as salt precursor was loaded to the MSA(x) using the Wet Impregnation (WI) and Ion Exchange (IE) method. The Co/SAM(x) was tested as a catalyst for hydrocracking of waste lubricant oil. The results showed that the MSA(100) has the highest acidity and optimum thermal stability with an average pore diameter of 3.37 nm, the pore volume of 0.87 cm 3 g –1 , and a surface area of 230.73 m 2 . The cobalt metal content loaded on the MSA(100) by WI and EI method was 0.50% and 0.15 wt.%, respectively. The hydrocracking of lubricant oil using Co/MSA(100)WI catalyst yielded a liquid fraction of 39.20 wt.% with selectivity for gasoline and diesel fraction of 29.30 and 9.48 wt.%. The Co/MSA(100)IE catalyst produced a liquid fraction of 28.10 wt.% with selectivity for gasoline and diesel fraction of 22.70 and 5.32 wt.%.

Used cooking oil catalytic cracking using Cr-charcoal ion-exchanged catalyst

Used cooking oil is the largest waste that can be converted into biofuel as a renewable alternative energy source with catalytic cracking process. In this study, used cooking oil was cracked using a Cr-Carbon catalyst. The charcoal was produced from solid waste (shell) of oil palm industry. Three different chromium concentrations (1, 2, and 3%) were used for the ion-exchange process of Cr-charcoal to produce the catalyst. These catalysts were used for the catalytic cracking of used cooking oil at three levels of temperature (450, 500, and 550°C). X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis were used for catalyst characterization. SEM-energy dispersive X-ray spectroscopy (EDX) analysis indicates that Cr was successfully adsorbed into the catalyst. The highest oil fraction was obtained from catalytic cracking of used cooking oil at 450°C using Cr-charcoal catalyst synthesized using 1% Cr solution.

Investigation on the stability of copper modification of SAPO-34 catalysts in NH3-SCR reaction after hydrothermal aging

The influence of hydrothermal aging on the structural stability of Cu-modified SAPO-34 prepared by ion-exchange and impregnation methods was studied. XRD, Ar adsorption at −196 °C, solid-state NMR, UV–vis, H2-TPR, and EPR were used to probe the structural properties of the catalysts. It was found that the precipitation of crystalline AlPO4 and SiO2, the appearance of mesopores, the migration of silicon to form siliceous islands, and the formation of copper oxide crystallites occurred in aged catalysts. Furthermore, more siliceous islands and copper oxide crystallites were present in the aged samples prepared by the impregnation method than in those prepared by the ion-exchange method. Therefore, the impregnated catalysts show a much poorer structural stability than the ion-exchanged catalysts, which leads to more serious deterioration in the NH3-SCR reaction after hydrothermal aging.

Probing cobalt localization on HZSM-5 for efficient methane dehydroaromatization catalysts

A new catalyst family of Co-exchanged HZSM-5 zeolite catalyst without additional active metals was for the first time modeled for the non-oxidative conversion of methane toward aromatics, which provides an alternative and promising way to produce aromatics from huge methane resources compared with the traditional routes from coal and crude oil. The prepared catalyst contains a well-defined Co site in the HZSM-5 zeolite anchored at Brønsted acid sites and is much appropriate for activating CH bond in CH4 for controllable formation of CHx species rather than coke. Over the Co-exchanged HZSM-5 catalyst, the maximum selectivity to total aromatics (mainly benzene and naphthalene) over 80% could be obtained. Compared to almost all non-Mo-based catalysts including V, Cr, Mn, Fe, Zn, Cu, Ga and W investigated in literature, the Co-exchanged catalysts exhibited several times higher TOF values (s−1). To corroborate the distinct Co speciation associated with the ion-exchanged catalyst and illustrate the structure–activity relationship of the well-modeled catalyst, a series of comparative activity experiments, various spectroscopic and microscopic techniques (ICP-AES, XRD, FT-IR, XPS, UV–Vis DR, and TEM) and chemical transient experiments (H2-TPR, CO-TPR, NH3-TPD) and DFT calculations were performed. The exchanged Co(II) species connected with zeolite framework are much stable in reductive gases and could not be reduced and carburized, which should be the active sites for appropriately activating CH4 into CHx species available for subsequent aromatic formation. DFT calculations confirmed that these Co-exchanged sites required much higher energy for the dissociation of CH bond in CH4 than supported Co clusters, suggesting that the formed CHx species have a low possibility of further cleavage of CH bonds and are stable for the subsequent aromatization reactions. The distinct Co locations and chemical states in HZSM-5 showing different catalytic behaviors has actually provided us a new insight into how to construct an active metal-zeolite catalyst for selective conversion of CH4 to value-added chemicals.

Saloplastics as multiresponsive ion exchange reservoirs and catalyst supports

The dynamic aspect of saloplastics allows cation exchange with a tuneable molality, enabling designing Cu(0) supported catalysts for CO oxidation.

Surface Acidity of Sulfuric Acid Activated Maredan Clay Catalysts with Boehm Titration Method and Pyridine Adsorption-FTIR

The acid or base of the solid surface is a very interesting aspect at the structure of surface and important in the field of ion exchange and heterogeneous catalysts. The use of clay as a heterogeneous catalyst is due to its acidity. In this paper, the acidity of heterogeneous catalysts Maredan clay activated by sulfuric acid was examined by the Boehm titration and adsorption pyridine method. In this study, Maredan clay was activated with several variation concentration of sulfuric acid (0.5, 1, 2 and 3 M) by impregnation method. The mixture was refluxed at 80°C for 3 hours, washed with double deionised water, dried and calcined at 500 °C for 3 hours. The results showed that activation of Maredan clay by sulfuric acid produced the total acid amount of 0.6483 mmol/g catalyst by using Boehm titration method and 1.1137 mmol/g catalyst by using pyridine vapor adsorption method. FTIR analysis of the spectra of pyridine adsorption was seen that the acid site of the Maredan clay catalyst activated by sulfuric acid dominant was Lewis acid site, with wave numbers at 1449.57; 1490.07; 1573.98 and 1616.42 cm−1.

Production of Cyclohexyl Acetate u sing Batch Reactor and Reactive Chromatography

Production of cyclohexyl acetate by reaction between acetic acid and cyclohexanol using ion exchange catalyst Amberlyst - 15 presented in this work. Batch experiments were carried in batch reactor using variables such as agitation speed, catalyst size, temperature, mole ratio, catalyst loading, moisture content, catalyst reusability. Simulation also carried out using ACM. Activation energy found to be 10000 J/g.mole. Reactive chromatographic reactor is also used for process intensification. Results obtained from batch and reactive chromatographic reactors were compared. More conversion obtained in reactive chromatographic reactor as compared to batch reactor.

Batch and Continuous Flow Production of 5-Hydroxymethylfurfural from a High Concentration of Fructose Using an Acidic Ion Exchange Catalyst

5-Hydroxymethylfurfural (HMF), a product of catalytic dehydration of C6 sugars, is a versatile and key renewable platform chemical. The possibility to use a high substrate concentration with high y...

Spectroscopic Evidence for the Involvement of a Radical Intermediate in the Friedel-Crafts Benzylation Using Ion-Exchanged K10 Catalysts

For Friedel-Crafts alkylation of aromatic hydrocarbons an ionic reaction path is considered as classical reaction mechanism. The alkylation with benzyl chloride in the presence of ion-exchanged K10 montmorillonite catalysts containing multivalent, reducible cations had an outstanding activity, therefore a radical initial step as a supplement to the ionic mechanism was proposed earlier. We made ESR investigations to clarify the existence and the nature of the suggested radical species. The ESR experiments verified that the reaction involves a radical step.

Effect of Pd- precursor and support acid properties on the Pd electronic state and the hydrodesulfurization activity of Pd-zeolite catalysts

We studied on the function of Pd species located in mesopores and inside zeolite channels (micropores) of the montmorillonite-modified zeolite catalyst for the hydrodesulfurization of diesel fraction with 350 ppm of sulfur as DBT, 4-MDBT, and 4,6-DMDBT. It was shown that the ex-dihydrogentetrachloropalladate impregnated catalyst as well as the ex-tetraamminepalladium(II) chloride ion-exchanged catalyst have high efficiency of sulfur removal from the diesel fuel in temperature range 280–300 оC.The sulfur tolerance of catalyst depended on the method of Pd adding. The catalyst prepared by ion-exchange with tetraamminepalladium chloride solution exhibited the highest sulfur tolerance. According to FTIR of adsorbed CO, this catalyst contains a small Pd metal atoms or cluster in electron-deficient state inside zeolite channels. They probably ensure sulfur tolerance due to hydrogen spillover.The montmorillonite addivite significantly modifies performance of the Pd-Zeolite catalyst in hydrotreating of diesel fraction. It leads to a decrease of cracking function, while those of hydrogenolysis of sulfurorganic molecules and hydrogenation of aromatic molecules are strengthened in comparison with the unmodified catalyst. This effect is explained by the change of acidic properties of the catalyst, limitations of diffusion of various molecules into the zeolite channels, and diffusion of Pd from the zeolite channels.