Aluminosilicate Catalysts Research Articles

Methanation of Carbon Dioxide on Co-Containing Aluminosilicate Catalysts

Methanation of Carbon Dioxide on Co-Containing Aluminosilicate Catalysts

Conversion of beechwood organosolv lignin via fast pyrolysis and in situ catalytic upgrading towards aromatic and phenolic-rich bio-oil

Lignin, an abundant renewable biopolymer found in plant cell walls, is enriched in phenolic units within its complex molecular structure. Unlocking its potential as alternative feedstock in (bio)refining has posed a long-standing challenge, even though it holds immense promise for replacing fossil-derived phenolic and aromatic compounds. This study focuses on fast pyrolysis as effective thermochemical depolymerization method of lignin, coupled with the in situ catalytic upgrading aiming to produce valuable bio-oil enriched in dealkoxylated (alkyl)phenolic and aromatic compounds. Lignin was isolated via the organosolv process from beechwood sawdust (hardwood biomass). Various acidic aluminosilicate catalysts (e.g., zeolites, such as ZSM-5, Beta and USY, and amorphous silica alumina) were applied, having different Si/Al ratio, porous and acidic properties. Fast pyrolysis experiments were conducted on a fixed-bed bench-scale reactor at two distinct temperatures (500 and 600 °C), employing different contact times and lignin-to-catalyst ratios. Non-catalytic pyrolysis experiments revealed that higher temperature, significantly influences bio-oil’s composition and yield, resulting in the conversion of initially formed alkoxy-phenols to alkyl-phenolic compounds, reaching a 47% relative concentration at 600 °C, while also yielding high amount of bio-oil up to 43 wt%. Among the catalysts tested, zeolite ZSM-5 (Si/Al=40) proved to be the most efficient, shifting the chemical profile of bio-oil from phenolic to aromatic (mainly BTX) with relative concentration of 57%, owing to its unique microporous structure and acidity. Depending on the catalyst type, a balance between BTX monomer aromatics and naphthalenes was observed. Lignin, as well as the obtained products (bio-oil, non-condensable gases, char/coke-on-catalyst) were thoroughly characterized using various analytical techniques. The catalytic upgrading results were associated with the physicochemical properties of the catalysts, providing valuable insights into the underlying reaction mechanisms.

The mechanism of oleic acid deoxygenation to green diesel hydrocarbon using porous aluminosilicate catalysts

The role of mesoporous solid acid aluminosilicate in the oleic acid deoxygenation was elucidated using ZSM-5 and Al-MCM-41 impregnated with Ni. The mesoporous supports were synthesized using a similar initial Si/Al ratio but employing different templates to vary the mesopores. ZSM-5_T produced interparticle mesopores when using TPAOH (tetrapropylammonium hydroxide) as a template. Meanwhile, ZSM-5_S with a well-defined intraparticle mesoporous channel was formed using a silicalite template. Al-MCM-41 synthesized without a template produced one-dimensional highly ordered mesoporous channels. The arrangement of mesoporosity in aluminosilicate determined the mechanistic pathway of oleic acid conversion into hydrocarbon. Oleic acid underwent primary thermal cracking into carboxylic acid before progressing into the subsequent decarbonylation reaction. The diesel hydrocarbon yield was enhanced following the order of Al-MCM-41>ZSM-5_S>ZSM-5_T>blank reaction. Large intraparticle mesoporosity produced long-chain carboxylic acid from catalytic cracking of oleic acid, which was subsequently deoxygenated into long-chain hydrocarbons.

Preparation and performance of aluminosilicate fibrous porous ceramics-supported catalyst for NOx removal

In this study, we report a new aluminosilicate fibrous porous ceramics-supported catalyst for the removal of [Formula: see text]. The influence of raw materials and sintering process on the structure and properties of aluminosilicate fibrous porous ceramics was studied. The composition and the structure of the catalysts were characterized by XRF, XRD, SEM-EDS, and XPS analysis, and the experiments of denitrification were performed to determine the influence of the porous structure and the calcination process on the denitrification efficiency. The results indicated that the glass fibers facilitate the formation of a uniform porous network structure within aluminosilicate fibrous porous ceramics, and that the optimal sintering temperature is 1000∘C. Under the condition, the loaded catalysts were highly dispersed on the surface of aluminosilicate fibrous porous ceramics, which possessed high porosity and large average pore sizes. The aluminosilicate fibrous porous ceramics-supported catalyst exhibited excellent denitrification efficiency and catalytic stability, which is expected to be used for the treatment of [Formula: see text] in flue gas.

Aromatization patterns of hexane in high silicon zeolite

In this article, methods of preparation of catalysts in analogues of in high-silica zeolite, conversion of n-hexane in the catalysts keeping in high-silica zeolite, of n-hexane to aromatic hydrocarbons, n-hexane to aromatic hydrocarbons in catalysts with high catalytic activity and selectivity modified with copper, 2%Cu*8%Zn/Н-High silica zeolite-40 conversion of n-hexane to aromatic hydrocarbons in the composition catalyst, activity in chain branching and aromatization processes to obtain high-octane components of fuels 2%Cu*8%Zn/Н-High silica zeolite-40 high silicon, A mesoporous aluminosilicate catalyst with high catalytic activity and selectivity was studied for the catalytic Aromatization of n-hexane to aromatic hydrocarbons. H-High silica zeolite-40 and 2%Cu*8 %Zn/H-High silica zeolite-40 catalysts with high catalytic activity and selectivity selected for catalytic Aromatization of n-hexane to aromatic hydrocarbons, Aromatization, chain branching and carbon-carbon by hydrogen action activity in the process of breaking the bond was studied.

Conversion of NOx over Aluminosilicate Cu-CHA Zeolite Catalysts Synthesized Free of Organic Structure-Directing Agents

Cu-CHA zeolites have proven to be effective for NOx reduction, but a drawback in using CHA zeolites is the cost associated with using expensive organic structure-directing agents. To overcome this drawback, we are reporting here the synthesis of Cu-CHA zeolite catalysts in both their NH4-form as well as K-form that do not require the use of organic structure-directing agents. After comprehensive characterization by XRF, XRD, 27Al NMR spectroscopy, FE-SEM, SEM/EDS, N2-adsorption/desorption, NH3-TPD, H2-TPR, and XPS, the zeolite catalysts were tested for NOx conversion by NH3-selective catalytic reduction (NH3-SCR). Cu-NH4-CHA zeolite catalysts exhibited remarkable activity and thermal stability over a wide temperature window, outperforming their counterpart K-forms. Among the NH4-forms of CHA zeolite catalysts, the 0.1 M Cu-NH4-CHA showed the best catalytic performance, achieving 50% NOx conversion at a temperature as low as 192 °C, and reaching full conversion of NOx at 261 °C. These Cu-based CHA zeolite catalysts are promising thanks to their environmentally friendly synthesis and offer the opportunity of maximizing DeNOx strategies in applications for NOx pollution abatement.

Investigation of physicochemical processes taking place in chemically activated very high volume fly ash mixtures

In order to reduce the negative impact of cement production on the natural environment, and in particular to reduce CO2 emission, new types of binders are sought. It is beneficial to use supplementary cementitious materials, such as fly ash. A very high volume of fly ash and a reduced amount of cement in the binder can, however, result in deterioration of some properties of the final composite. Such systems require activation. The aim of this work was to investigate the effects of different activators: spent aluminosilicate catalyst (very active pozzolanic material), Na2SO4 and Ca(OH)2 on the hydration/activation processes and development of 28-day compressive strength of the blends containing a very high volume of fly ash. Activators were introduced into the system in various combinations: alone or in mixtures. The following research methods were used: calorimetry, thermal analysis, X-ray diffraction and IR spectroscopy. It was shown that each type of activation accelerates cement hydration, improves pozzolanic activity and increases compressive strength compared to the results of non-activated reference sample. However, the activation kinetics and mechanism of interaction are different for different activators. The most promising results were obtained for the combination of three activators: spent aluminosilicate catalyst, Na2SO4 and Ca(OH)2.

Hydrophobicity Boosts Catalytic Activity: The Tailoring of Aluminosilicates with Trimethylsilyl Groups**

AbstractIntroducing organic groups into metal silicate catalysts and thus supposedly changing the surface hydrophobicity has been shown to enhance the catalyst performance in various reactions. However, the organic groups introduction does not unambiguously guarantee hydrophobicity control. Therefore, a thorough characterization is necessary to provide a complete view of the interaction between the catalyst surface, reactants, and products. Herein, an aluminosilicate catalyst with well‐dispersed Al atoms was prepared via the non‐hydrolytic sol‐gel method. This material was post‐synthetically modified with trimethylsilyl groups; their number on the catalyst surface was controlled via a temperature‐vacuum pretreatment. In such a way, aluminosilicate materials with similar porosity, structure, and acid site strength and quality were obtained. Notably, the water sorption measurements showed that trimethylsilylated aluminosilicates adsorb 2.5–3 times less water than the parent material (p/p0=0.3). The turn‐over‐frequency in epoxide ring opening and ethanol dehydration scaled up with the number of trimethylsilyl groups grafted on the catalyst surface. Particularly, the heavily trimethylsilylated sample achieved three to five times higher turnover‐frequency in styrene oxide aminolysis than the parent aluminosilicate material. To the best of the authors’ knowledge, it exhibited the most active Al sites for epoxide aminolysis in the present literature.

Optimization and kinetic studies of 12-tungstophosphoric supported mesoporous aluminosilicate through response surface methodology for biodiesel production using green seed canola oil

Biodiesel synthesis using a non-edible feedstock obtained from green seeds of canola oil using 12-tungstophosphoric heteropoly acid supported mesoporous aluminosilicate (HPW/MAS) catalyst was conducted. Response surface methodology (RSM) based on central composite design (CCD) approach was implemented to study the effects of catalyst loading, methanol to oil (M/O) molar ratio, and reaction time on biodiesel yield. A polynomial quadratic model was developed as a suitable model to correlate the reaction parameters to the response. M/O molar ratio indicated the most effect on biodiesel yield owing to the reversible nature of this reaction, while catalyst loading had minor effect on it. The highest biodiesel yield of 89 % was obtained at optimum reaction conditions of 5.9 wt% of catalyst loading, 27.2 of M/O molar ratio, at 200 °C and 4 MPa for 8 h. The formation of biodiesel was verified using HPLC, NMR and GC–MS analyses for their functional groups corresponding to esters. Kinetic study was carried out with pseudo first order assumption at various reaction temperatures in the range of 160 to 200 °C. From the Arrhenius equation, the pre-exponential factor and activation energy were found to be 9.1 × 102 min−1 and 36.34 kJ/mol, respectively.

Aluminosilicates Catalysts Synthesis from Low-Grade Indonesian Kaolin for the Acetalization Reaction

Aluminosilicate and ZSM-5 catalyst were synthesized from local materials, low-grade Indonesian kaolin. High quartz impurities content in the low-grade kaolin was successfully reduced by the consecutive treatment process including washing, centrifugation, and Fe3+ treatment. All the synthesized catalyst showed mesoporous structure with pore diameter around 3.5 nm. The catalytic activity was investigated in the acetalization of 3,4-dimethoxybenzaldehyde and propylene glycol, then the effect of a different base (TPAOH and NaOH) and Fe3+ addition in the treatment process to the catalytic activity was discussed. The catalytic activity of the aluminosilicate catalyst outperforms the ZSM-5. Interestingly, it is found that the catalytic activity of the catalyst can be enhanced by addition of Fe3+ in the aluminosilicate, with enhanced the conversion from 32.2% to 81.6%, whereas Fe3+ addition to ZSM-5 showed slightly increased conversion value from 0% to 3.65%. All catalysts showed high selectivity of 100% of the reaction product 2-(3,4-dimethoxy-phenyl)-4-methyl-1,3-dioxolane.

Получение бензиновой фракции в процессе гидрокрекинга мазута

In the article, a new processing technology is presented in the «Hydrocracking of heavy oil residues» (SPR-1) unit with the presence of highly dispersed aluminosilicate catalysts suspended in fuel oil. The hydrocracking process of fuel oil obtained from Baku oils was studied with the participation of catalysts modified by means of ion exchange and impregnation methods of Az-4 mineral. The main results of the study on the production of gasoline fraction by hydrogenation of heavy oil residues under low pressure with the presence of purchased catalysts are presented.It was determined that under optimal conditions 6% of fuel oil hydrocracking without catalyst; 26% with 2.5% Az-4 addition. When Az-4 catalyst modified with Ni and Mo by impregnation and ion exchange methods is used, the yield of gasoline fraction is 32 and 34.45% by mass, respectively. It was shown that the amount of sulfur, unsaturated hydrocarbons and iodine in the gasoline fraction decreased. The octane number increases from 64 to 71.The composition and properties of the obtained gasoline fraction were studied by NMR and IR spectroscopy methods.

Highly selective aromatization of light naphtha using mesoporous aluminosilicate catalysts and theoretical model for predicting activity

Highly selective aromatization of light naphtha using mesoporous aluminosilicate catalysts and theoretical model for predicting activity

Hydrodeoxygenation of Bio-oil Components Containing a Guaiacol Fragment in the Presence of a Ruthenium-Suppoting Mesoporous Aluminosilicate Catalyst

Hydrodeoxygenation of Bio-oil Components Containing a Guaiacol Fragment in the Presence of a Ruthenium-Suppoting Mesoporous Aluminosilicate Catalyst

Catalytic advances in vacuum gas oil hydrocracking

Hydrocracking still maintains the pivotal role in the industry owing to the production of highly demanded transportation fuels. Having comprised pretreatment of VGO, comparative research onrecent catalysts, this review paper provides athorough picture about all consecutive steps in the hydrocracking process of vacuum gasoil. Discussing recovery of VGO from vacuum residue with minimum sulfur content, the focus was put on the catalyst characterizations and their influence on the conversion of VGO, the yield of middle distillate, gasoline as well asnaphtha. Both zeolite and amorphous catalysts have undergone a comparative analysis interms of their hydrocracking properties as well as catalytic activities during provided conditions. The article also examines the process of hydrocracking of vacuum gas-oil from Baku oils with the participation of modified aluminosilicate catalyst containing Ni, Mo to obtain high-quality raw materials for environmentally friendly diesel fuel and catalytic cracking process. The hydrocracking process of vacuum gas-oil conducted at 3-8 MPa pressure, 400-450 °C temperature range, in a flow-type Hungarian unit with a reactor capacity of 200 ml. During the investigations of temperature on hydrocracking process it was revealed that, when temperature rises from 400 to 460 °С the yield of diesel fraction increases from 35 to 50% wt. The yield of gasoline fraction constitutes 0-6% wt. and the produce of residue fraction decreases from 65% to 45%. With increasing of temperature from 400 °C to 450 °C the amount of sulphur decreases from 0.01% to 0.005% in composition of diesel fraction. Keywords: vacuum gasoil; hydrocracking; diesel fraction; alumosilicate; catalyst; hydrodesulfurization.

PARTIAL CATALYTICAL PROPANE OXIDATION ON ALUMOSILICATE CATALYSTS

In the scientific literature the problem of obtaining highly selective aluminosilicate catalysts is related to the study of the influence of the nature of active centers (acidity of their surface) on the catalytic activity. In some cases a linear dependency can be observed between the rate of acidity and catalytical activity. The acidity of alumosilicates, in its turn, is considerably dependent on the mode of their preparation. In case of preparing alumosilicates by joint precipitation with the increase of Al2O3 rate from 0.1 to 1.0% the concentration of acid centers increases in proportion with aluminum oxide contents. With further increase of aluminum oxide rate the concentration of acid centers increased more slowly whereas at Al2O3 rate of 75% the concentration of acid centers decreased. In this work physical and chemical properties of five alumosilicate catalysts with different content of aluminium oxide in them are synthesized and analyzed. The reaction of propane oxidation by air oxygen was investigated to define the influence of alumosilicates’ active centers on the catalytic process. In all specimens of alumosilicates the reaction products were as follows: formaldehyde, acetic acid, CO, CO2, C3H6, H2, H2O, as well as acetic aldehyde were found in small amount. At high (above 770 K) temperature CH4 and C2H4 were found. The possibility of obtaining of formaldehyde and acetic acid with high selectivity is demonstrated. The catalysts’ activity in the reaction under study accounts for aluminium oxide in their content the acidity of the surface. A suggestion is made about the possibility of the formation of formaldehyde and acetic acid on different active centers of the catalyst. On the basis of the research and relevant literature a scheme of propane oxidation on alumosilicate catalysts is proposed.

A Novel Model Parameter for the Assessment of the Dimerization of n-Butenes over Ni-Containing Aluminosilicate Catalysts

Previous investigations on the dimerization of n-butenes over Ni-containing Al-MCM-41/ZSM-5 mixed-phase catalysts have shown a correlation between the conversion and the Ni/(Al + Ni) ratio as well as between the conversion and the metal–support interaction, which is represented by the reduction degree. In the present work, both approaches are combined to a novel model parameter, which allows to determine the proportion of active Ni species on the Al-Ni site pairs and thus provides crucial insights into formation of catalytically active nickel sites as well as their effects on the selective formation of low-branched dimers.

Controlled methylamine synthesis in a membrane reactor featuring a highly steam selective K+-LTA membrane

Water permeation through a hydrophilic zeolite membrane can be used to promote reactions under equilibrium controlled conditions through the in situ removal of the by-product water. In the methylamine synthesis, mono- (MMA), di- (DMA) and trimethylamine (TMA) are formed by the successive methylation of ammonia with methanol (MeOH) over a mildly acidic catalyst. The methylamine yield can be increased through selective water extraction from the reactor through a membrane. Since both reactants and water have similar molecular kinetic diameters below 3.7 Å, because of the limited steam selectivity of the commonly used hydrophilic Na-LTA membrane (zeolite 4A), not only water has been removed. Therefore, in this work a K-LTA membrane, which was obtained by ion exchange with a reduced pore window diameter of 3 Å and thus with a higher water selectivity, was used in the membrane-supported methylamine synthesis. When replacing the Na-LTA with the K-LTA membrane, the H2O/MeOH mixed gas separation factor increases up to 1100 and the H2O/NH3 separation could also be improved. This in turn leads to an overall boost of the higher methylated amines DMA and TMA in methylamine synthesis. When using the narrow-pore aluminosilicate catalyst H-SSZ-13 with CHA structure, the application of the K-LTA membrane increases the share of the industrially desired product DMA from 51% without membrane to 74% with slightly increased conversion. When using the large-pore catalyst H-MOR, the thermodynamically most stable product TMA can be formed and the selectivity was increased from 35% without membrane to 41% with the K-LTA membrane.

Influence of the porosity and acidic properties of aluminosilicate catalysts on coke formation during the catalytic pyrolysis of lignin

Five aluminosilicate catalysts with different textural and acidic properties are used to study the influence of their acidic and porous properties on the coke formation during the fast catalytic pyrolysis of lignin. The competition between coke formation and target product (hydrocarbons) formation in regard to different pore sizes and Si/Al ratios is classified via performing X-Ray Diffraction (XRD), nitrogen adsorption-desorption, pyrolysis–gas chromatography–mass spectrometry (Py-GCMS), kinetic calculations, and thermogravimetric (TG)/temperature programmed oxidation (TPO) measurements. The results indicated that a pore size consistent with the critical diameters of the pyrolysis products of lignin is a prerequisite for a catalyst to reach a high selectivity for the desired products with less coke formation. A relatively large pore size can cause severe coke formation; however, large pores are favorable for increasing the reaction rate by increasing the diffusion efficiency. A catalyst with sufficient acidity is also essential for high selectivity towards target products.

Hydration Processes of Four-Component Binders Containing a Low Amount of Cement.

Results of research on hydration of four-component binders containing very high amounts of supplementary cementitious materials were presented. The samples were composed of blended pozzolana (a mix of conventional fly ash and spent aluminosilicate catalyst), cement (about 20 wt.% in the binder) and Ca(OH)2. Spent aluminosilicate catalyst was proposed as activating component which can improve properties of low-cement blends, while the role of Ca(OH)2 was to enhance pozzolanic reaction. Early and later hydration periods of such blends were investigated by calorimetry, TG/DTG, FTIR and X-ray diffraction. Initial setting time as well as compressive strength were also determined. It was concluded that enhancement of reactivity and improvement of properties of fly ash–cement binders are possible by replacing a part of fly ash with more active fine-grained pozzolana and introducing additional amounts of Ca(OH)2. The spent catalyst is mainly responsible for accelerating action during the first hours of hydration and for progress of early pozzolanic reaction. Fly ash develops its activity over time, thus synergic effect influences the later properties of composites. Samples containing blended pozzolana exhibit shorter initial setting times and higher compressive strength, as well as faster consumption of Ca(OH)2 compared to the reference. Investigated mixtures seem to be promising as “green” binders, alternatives to cement, after optimizing their compositions or additional activating procedure.

The mesoporous aluminosilicate application as support for bifunctional catalysts for n-hexadecane hydroconversion

Abstract Mesoporous aluminosilicate (MAS) and bifunctional catalysts based on it were synthesized. The MAS synthesis is based on the method of copolycondensation of silicon and aluminum sources in the presence of alcohol. Hexadecylamine was used as a template for the formation of a porous structure. The catalysts were characterized by X-ray diffraction, Brunauer–Emmett–Teller, temperature-programmed desorption of ammonia, hydrogen-temperature programmed reduction, Fourier transform infra-red spectroscopy, and diffuse reflectance infrared Fourier transform spectroscopic methods. The catalytic activity of Ni/MAS-H-bentonite and Mo/MAS-H-bentonite was investigated during the hydroconversion of n-hexadecane. It has been shown that a sample promoted with molybdenum and nickel based on MAS has the high activity and selectivity in the process of n-hexadecane hydroisomerization under optimal conditions (320°C, atm pressure).