Accessibility Of Acid Sites Research Articles

Noble metal-free tandem catalysis enables efficient upcycling plastic waste into liquid fuel components

The lack of effective approaches for upcycling waste plastic has led to severe environmental pollution and squandering of carbon resources. While hydrocracking macromolecular polyolefins over typical metal-zeolite catalyst produces high quality liquid fuel components, the limited activity of base metal and restricted accessibility of acid sites within microporous zeolite renders this process still not in practical scale. A tandem catalyst comprising Ni-WO3/Al2O3 and Beta zeolite was developed for consecutive hydrocracking polyolefins, achieving a yield of 86.2 % of primarily gasoline-jet ranged hydrocarbons (mainly C5-C16 and minor C16+) at 280 °C. The incorporation of tungsten species onto Ni/Al2O3 largely enhances the surface acidity and accelerates the primary cracking process that converts polyethylene (PE) into medium-sized intermediates, which would readily diffuse into the pore networks of Beta and undergo further cracking to yield desired liquid hydrocarbons. In addition, this tandem catalyst also promotes facile hydrocracking of consumer-grade plastic waste and maintains excellent stability over 5 recycling tests. The noble-metal-free catalyst achieves an impressive liquid formation rate of 5.74 g·gcat.−1·h−1, rivaling the noble metal-based catalyst and demonstrating high application prospects.

Synthesis and consequence of three-dimensionally ordered macroporous Beta zeolite supported NiW catalyst for efficient hydrocracking of 1-methylnaphthalene to BTX

The three-dimensionally ordered macroporous Beta (3DOM-Beta) zeolite was prepared and used as support of NiW sulfide catalyst for hydrocracking. The as-prepared NiW/3DOM-Beta catalyst possessed a high specific surface area and external specific surface area up to 499 m2/g and 241 m2/g, respectively, and a small average layer length (3.62 nm), a high highest average stacking number (4.64) and dispersion (fW=0.24) of metal sulfide phase, which are characteristic of high hydrogenation activity. Its high mesopore volume (0.25 cm3/g) and the highly ordered interconnected macro-meso-microporosity hierarchical structure significantly facilitated diffusive mass transfer. Compared to the NiW sulfide supported on conventional Beta (C-Beta), alkali-treated Beta (A-Beta) and nanosized Beta (Nano-Beta) zeolites, NiW/3DOM-Beta catalyst showed the highest BTX selectivity and yield of 40.7 % and 40.2 % (33.2 % and 32.6 % on NiW/C-Beta, 34.8 % and 33.9 % on NiW/A-Beta, 37.2 % and 36.6 % on NiW/Nano-Beta), and the highest hydrocracking activity (TOF=2.11 × 10-2∙s−1) as well as the smallest coking content (6.7 wt%). This work not only reveals the promotion effects of the ordered mesopore structure of supports on metal dispersion, accessibility of acid sites, diffusion of reactants and products for designing hydrocracking catalyst, but also shows the potential practical application of 3DOM zeolites with interconnected macro-meso-microporosity for the efficient catalytic conversion of macro-hydrocarbons via hydroupgrading.

Tailor-made the ultrathin nanosheet and acid site accessibility of mordenite zeolite for carbonylation of dimethyl ether

Precisely tailored nano-morphology and crystal growth endures mordenite (MOR) zeolites with reduced internal diffusion resistance, enabling greater accessibility of existing acid sites to further stimulate catalysis. Controllable synthesis nanosheet MOR zeolite thinner than 20 nm along at least one dimension is highly attractive but remains great challenge. Herein, c axis along the [001] direction shortened MOR nanosheets with a thickness of 10–20 nm was synthesized. As expected, the mass transfer performance over the nanosheet sample is significantly improved by 2.5 times compared with the conventional nano-morphology. Furthermore, more Brønsted acid sites (BAS) can be induced into 8-membered ring (8-MR) pores in the nanosheet MOR zeolite. The conversion of dimethyl ether (DME) to methyl acetate over the ultrathin MOR zeolite is increased from 17.4 % to 71.7 % compared to that of the conventional nanoparticle. The DME conversion was stable at 70.0 % after reaction 80 h, when the acid sites located in 12-membered ring pores was poisoned by the pyridine molecule. Unexpectedly, we discovered that the desorption behavior of pyridine is also influenced by the accessibility of acid site, not only by the amount of BAS in 8-MR. The unique nanosheet structure with short c axis reduces the spatial stability of pyridine adsorbed on BAS in the 8-MR side pocket and the BAS in the 8-MR side pocket can be recovered at lower temperatures. Herein, a new insight into of DME carbonylation catalyzed by ultrathin nanosheet of MOR zeolite is revealed.

Active site requirements for bio-alcohol dehydration: Effect of chemical structure and site proximity

Synthesis-structure-activity relations are reported, describing how interzeolite conversion (IZC) allows synthesis of ZSM-5 (MFI framework) with fixed physicochemical properties, except the variable local acid site (Al) arrangement, by variation of the synthesis time. Local confinement and acidity effects are probed by applying both H-ZSM-5 and Na-ZSM-5 samples in alcohol dehydration. Pyridine and divalent cobalt ion probing are used to quantify the amount of accessible acid sites and of Al in close proximity. Al in close proximity shows a strong influence on n-butanol dehydration turnover rates. The turnover rates are also strongly dependent on local confinement: in Na-form, ZSM-5 synthesized with more Al present as isolated species is a factor of 3–7 times more active than Na-ZSM-5 with fewer isolated Al. However if the zeolites are in proton form, ZSM-5 with more proximate sites show a higher activity compared to ZSM-5 with more isolated sites. Linear butene selectivity increases in Na-ZSM-5 compared to H-ZSM-5, caused by a suppressed dibutyl ether formation. The selectivity towards 1-butene is enhanced to a greater extent on proximate sites, likely due to a local/steric constraint at the active site. Decomposition of DBE over Na-ZSM-5 is more active compared to n-butanol dehydration, independent of acid site proximity. Also for 2-propanol dehydration, Na-ZSM-5 is less active than H-ZSM-5, yet the activity difference is attenuated compared to n-butanol dehydration. Essentially, due to the intrinsic higher reactivity of 2-propanol, the acid site requirement is less stringent. These findings highlight the importance of local confinement and Al proximity in acid-catalyzed conversion of oxygenated compounds.

Organosilane-assisted synthesis of EU-1 nanozeolite aggregates with improved activity in catalytic cracking of n-hexane

One-dimensional microporous zeolite, EU-1, exhibits more favorable selectivity of propylene in cracking of petroleum components. However, it faced the problem of low catalytic activity for the poor utilization of active sites. In this work, dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (TPOAC) was used to functionalize protozeolitic units and inhibit the excessive growth of crystals by the long hydrophobic alkyl chain. The introduction of TPOAC decreased the crystal sizes into nanoscale, enhanced the mesoporous volume of EU-1 zeolite, and exposed more external acid sites. Moreover, TPOAC could interact with Al species, and in this case, fewer Al atoms were incorporated into the zeolite framework, reducing the acid strength and amount. Intelligent gravitation analyzer test indicated that the zeolite prepared with the presence of 0.30 g TPOAC exhibited the largest accessible volumes in n-hexane adsorption, and the highest accessibility of acid sites, which synergistically promoted cracking of n-hexane for the production of light olefins.

Synthesis of Al-enriched beta zeolite nanocrystals by using DABCO di-cationic quaternary ammonium as organic structure directing agent

Al-enriched Beta zeolite nanocrystals with densely populated acid sites and enhanced mass transfer efficiency have been demonstrated to show promising catalytic performance. In this work, low Si/Al ratio (8–9) Beta nanocrystals (about 20 nm) was synthesized by using DABCO based di-cationic quaternary ammonium salts as organic structure directing agent with high solid yield (＞95 %). The hydrothermal synthesis process was followed by monitoring the intermediate products at different time intervals, through which the key role of the di-cationic quaternary ammonium for the formation of Beta nuclei was identified. The promising catalytic performance of the Al-rich Beta nanocrystals in 1,3,5-triisopropylbenzene transalkylation with benzene was attributed to the high density and enhanced accessibility of acid sites.

Variation in Catalytic Efficacies of a 2D pH-Stable MOF by Altering Activation Methods.

Although it is well-known that the Lewis acidity of Metal-Organic Frameworks (MOFs) can effectively enhance their catalytic activity in organic transformations, access to these Lewis-acidic sites remains a key hurdle to widespread applications of Lewis-acidic catalysis by MOFs. Easy accessibility of strong Lewis acidic sites onto 2D MOFs by using proper activation methods can be a cornerstone in attaining desired catalytic performance. Herein, we report a new 2D chemically stable MOF, IITKGP-60, which displayed excellent framework robustness over a wide pH range (2-12). Benefiting from the abundant open metal sites (OMSs) and framework robustness, the catalytic activity of the developed material was explored in one-pot three-component Strecker reaction and Knoevenagel condensation reaction. Moreover, the developed catalyst is superior in catalyzing the reactions involving sterically hindered substrate (1-naphthaldehyde) with high turnover number. A comparative catalytic study was conducted using different activation methods (chloroform and methanol exchanged activated samples), highlighting the significant effect of activation methods on its catalytic performances. The sustainable synthetic pathway under solvent-free conditions for a broad scope of substrates using low catalyst loading and excellent recyclability made the developed pH-stable framework a promising heterogeneous catalyst.

Enhanced hydroisomerization performance over highly mesoporous ZSM-48 zeolites constructed by organosilane surfactant

One-dimensional ZSM-48 zeolite had been widely accepted as an acid support for the hydroisomerization of long chain n-alkanes. In current works, highly mesoporous ZSM-48 zeolites were fabricated by the assistance of 3-aminopropyltriethoxy-silane (APTES) by its strong self-condensation on the nanocrystal surface. The zeolites with enhanced mesoporosity were characterized by FTIR, XRD, N2-physisorption, NH3-TPD, Py-IR, SEM, TEM, etc. to investigate the changes in properties. The results suggested that the crystal of zeolite sizes, morphology, and porosity of ZSM-48 were controllably tuned, although the incorporation of APTES induced the loss of crystallinity and the increase of SiO2/Al2O3 ratio. The downsized ZSM-48 crystals with enhanced mesoporous structure could reduce diffusion channel direction length, as well as simultaneously improve the accessibility of acidic sites. The catalytic effect of n-hexadecane isomerization was evaluated in a reactor as fixed bed and the results showed that the properly addition of mesopore generating agent improved the catalytic activity compared with the Pt catalyst supported on parent ZSM-48 zeolite. The yield of i-C16 over Pt/ZSM-48–0.02 catalyst was achieved at approximately 81 wt%, with conversion of 93 wt%, and selectivity of 87 wt%. This proposed method presented a novel and straightforward approach for synthesizing highly mesoporous ZSM-48 zeolites.

Furfural Acetalization with Ethanol over Hierarchical vs. Conventional Beta Zeolites

AbstractA set of hierarchical Beta zeolites was synthesized using concentrated reaction mixtures and compared to conventional materials with a similar composition. The obtained zeolite catalysts were investigated in acetalization of furfural with ethanol at room temperature yielding a commercially valuable fuel additive (furfural diethyl acetal). The highest yield of the desired product (91 %) was achieved over a zeolite catalyst possessing developed mesoporosity (Vmeso 0.75 cm3/g) and a high external surface area (280 m2/g). The concentration of accessible acid sites was found to be responsible for high catalytic performance of the tested zeolitic catalysts.

Synthesis of Two-Dimensional Zeolite Nanosheets Applied to the Catalytic Cracking of a Waste Cooking Oil Model Compound to Produce Light Olefins.

Hierarchical zeolites can provide multidimensional spatial networks and, therefore, have significant potential as catalysts for the cracking of biomass to generate light olefins. The present work synthesized the diquaternary ammonium-type surfactant [C18H37-N+(CH3)2-(CH2)6-N+(CH3)2-C6H13]Br2, incorporating hydrophobic 18-carbon alkyl groups for usage as a structure-directing agent. This compound was subsequently used to prepare nanosheets of a hierarchical ZSM-5 two-dimensional zeolite (HNZSM-5) through a one-pot hydrothermal method. The crystal phase, morphology, and hierarchical structure of the HNZSM-5 were analyzed using various techniques, including X-ray diffraction, electron microscopy, and N2 adsorption/desorption. When applied to the catalytic cracking of a waste cooking oil model compound, the HNZSM-5 exhibited superior activity and stability compared with a conventional ZSM-5. This performance was attributed to the more accessible acid sites and unique lamellar structure of the former material. The HNZSM-5 also outlasted the conventional zeolite, showing deactivation after 45 h of reaction compared with 20 h, indicating exceptional stability and excellent resistance to coking.

Constrained and Open Mesoporosity in Polypropylene Cracking: Insight From Spectroscopic Investigations of Acidity, Diffusion, and Activity.

The outcome of the demetalation process of zeolites depends on applied treatment conditions and can lead to the formation of either open or constrained mesopores. The quaternary ammonium cations as pore-directing agents during desilication are responsible for developing constrained mesoporosity with bottleneck entrances. However, higher mesopore surface area and higher accessibility of acid sites are often found for the hierarchical zeolites with constrained mesopores. This is followed by better catalytic activity in the cracking of vacuum gas oil and polymers. For desilication with pure NaOH, a realumination process is observed and an additional acid-wash step is required to reach their full catalytic potential. Thus, this study aims to analyze the acidic and catalytic properties of hierarchical ZSM-5 zeolites of different mesoporosity types employing in situ and operando FT-IR spectroscopic evaluation of polypropylene cracking. The suitability of constrained mesoporosity is studied by assessing the neopentane diffusion in kinetic adsorption, Monte Carlo calculations, and rapid scan FT-IR spectroscopic measurement analyzed by Crank solution for diffusion. The FT-IR spectroscopic results of in situ and operando studies are supported by two-dimensional correlation analysis, allowing to establish the direction of changes seen on spectra and their order.

Study on the Regeneration of Waste FCC Catalyst by Boron Modification.

Regeneration has been considered as an ideal way for the post-treatment of waste FCC catalyst (ECat). In this work, the degeneration mechanism of ECat was firstly researched and attributed to the increasing of strong acid sites accessibility of ECat in contrast with fresh FCC catalyst by adsorption FTIR. Based on the proposed degeneration mechanism, ECat was successfully regenerated through suitable weakening for strong acid sites by boron modification. Characterization and evaluation results suggested that, the strong acid sites of regenerated ECat (R-ECat) were apparently decreased by boron modification which had significantly improve the heavy oil catalytic cracking performance of R-ECat. Because of the excellent performance, R-ECat in this work could successfully substitute for partial fresh FCC catalyst in FCC unit, which would provide a practicable way for the reutilization of ECat.

The effect of hierarchical pore structure SAPO-34 catalyst on the diffusion and reaction behavior in MTO reaction

Establishing the hierarchical pore structure is considered as a feasible approach for enhancing diffusion and improve catalytic efficiency of SAPO-34 zeolite in the methanol-to-olefin process. Nevertheless, under reaction conditions, the correlation among the diffusion behavior in the crystal, coke deposition behavior and catalytic performance of SAPO-34 catalysts with varying pore structures remains to be clarified. Herein, we revealed the structure–activity relationship between the hierarchical pore structure, the catalytic performance and the anti-coke deposition performance of the catalyst in the MTO reaction via the synergy of reaction–diffusion experiments and molecular simulation, then the mechanism of the hierarchical pore SAPO-34 catalyst to eliminate the diffusion limit and improve the accessibility of acid sites was clarified. The results demonstrated that the establishment of a hierarchical pore structure strengthened the diffusion of reactant methanol in the pores, leading to the diffusion resistance being reduced by 5 times and the diffusion coefficient being improved by two orders of magnitude. The key reaction rate-determining step shifted from micropores diffusion to the adsorption of acid sites in hierarchical pores, and the catalytic efficiency of the catalyst was increased by 3 times. Furthermore, with the establishing hierarchical pore technique, the expansion of the accommodation space for coke deposition led to a reduction in the blocking of pores due to coke deposition, particularly around the orifices. Moreover, the accessibility of the reactant molecules to the acid sites within the pores was enhanced, resulting in a balanced ratio between pore blockage and acid site coverage, thereby improving the anti-coke deposition performance of the SAPO-34 catalyst. This work can provide important foundational data and theoretical guidance for the study of reaction–diffusion synergistic interaction in zeolite catalysis reactions.

Synthesis of alkyl-branched fatty acids by isomerization on micro-mesoporous ferrierite-based zeolitic materials

The synthesis of alkyl-branched fatty acid methyl esters from fatty acids is of great interest to synthesize high value-added products. The isomerization reaction catalyzed by microporous zeolites is promising due to its high yields, but rapid deactivation is its main drawback. In this work, a micromesoporous ferrierite synthesized by a well-controlled alkaline recrystallization process, was evaluated as a catalyst in the isomerization of methyl oleate. Recrystallized materials present improved accessibility of acid sites at the mouth of 10-MR pores due to the increase of the mesopore surface. Methyl oleate isomerization has been implemented in batch conditions and in a continuous flow process with experiments lasting more than 3 days. Stable yield of branched isomers higher than 50% was reached at 285 °C and 3.5 h-1 WHSV. The catalytic results, combined with a detailed analysis of fresh and spent catalysts, has provided information on the phenomena involved, in particular deactivation.

Mechanistic understanding of metal–acid synergetic hydroconversion of polyethylene under mild conditions over a Ru/MOR catalyst

Hydroconversion has been demonstrated as a viable method to efficiently deconstruct polyolefins under relatively mild conditions. The hydrogenolysis of C–C bonds over Ru-based catalysts can convert polyolefins into liquid alkanes and methane. To suppress methane generation and obtain high-value isomer, further exploration of the mechanism for the cooperative deconstruction of polyolefins by bifunctional catalysts with metal–acid sites is necessary. In this study, we utilized ball milling to enhance the accessibility of acid sites within MOR zeolite, while the fragmented pore structure ensured that the loaded Ru metal was sufficiently accessible for long-chain alkanes. The sequential accessibility of metal–acid sites boosted the hydroconversion efficiency of low-density polyethylene (LDPE). Through systematic investigations involving catalysts with various Ru loadings and Si/Al ratio of zeolites, it is discovered that the smaller-sized Ru particles not only facilitate the generation and desorption of olefinic intermediates in hydrocracking but also promote the hydrogenation and desorption of alkyls and suppress the cascade of terminal C–C bond cleavage in hydrogenolysis. Liquid fuel (C5-C21) yield was increased by 27% for the catalyst loaded with 0.7 wt% Ru on mMOR20 compared to 1.7 wt% loadings, while methane yield was only one-third of the latter. Concurrently, the distribution of acid sites on the zeolite surface affected the aggregation process of Ru atoms. This study deeply unveils the synergistic interaction of metal–acid sites, facilitating internal C–C bond cleavage to obtain liquid fuel and sheds light on catalyst design for waste polyolefins upcycling.

Aminoacid-Assisted Synthesis of Hollow Hierarchical FER Zeolite with Improved Catalytic Performance.

Hierarchical zeolites are highly-desired catalysts in the petrochemical industry due to their shorter diffusion length, faster diffusion rate, and better accessibility to active acid sites compared with conventional zeolites. Herein, we report a simple aminoacid-assisted method to synthesize urchin-like hollow hierarchical FER zeolite with abundant mesopores and macroporous inner cavities. An aminoacid (i.e. L-lysine) is used to facilitate the agglomeration of primary nanoparticles, and the agglomerates with staged crystallization in the internal and surface. The preferential nucleation and crystal growth at the external surfaces together with the lagged crystallization of the inner core of the agglomerates results in the formation of hollow inner cavities after the exhaustion of interior materials. Thanks to the unique hierarchical structure and more accessible acid sites, the hollow hierarchical FER zeolite exhibits improved catalytic performance over the conventional one in the skeletal isomerization of 1-butene to isobutene.

Preparation and Catalytic Properties of Graphene Oxide/ Phosphotungstic Acid Composites

Background: Cellulose structures are in stable crystallineform. The hydrolysis of cellulose to small reducing sugars is difficult, but essential for its utilization Objective: To investigate the effect of graphene oxide (GO) loading on the catalytic performance of phosphotungstic acid (HPW) for the catalyzed hydrolysis of cellulose, with the purpose to get high yield of total reducing sugar (TRS). Methods: Graphene oxide/phosphotungstic acid (GO/HPW) composites were prepared using a liquid-phase composite method. The materials were applied to catalyze hydrolysis of microcrystalline cellulose in 1-butyl-3-methylimidazole chloride ionic liquid ([Bmim]Cl). The samples were characterized by Powder X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), Field emission scanning electron micrographs (FE-SEM), pyridine IR and acid-base chemical titration. Results: The Brønsted acidic sites were the main source of acidity in the composites and its concentration was determined to be 0.96 mmol/g. With the use of the GO/HPW composite as catalysts for cellulose hydrolysis, TRS yield of 90.5 % was obtained. Conclusion: GO/HPW composites retained the functional groups of both materials. It was the Brønsted acidic sites in the materials that effectively promoted the cellulose hydrolysis reaction. The structures of GO/HPW with the agglomeration of HPW scattered on GO had high accessibility of acidic sites and fast mass transfer of the reducing sugars to the outside of the catalysts in time to prevent their further conversion into by-products. TRS yield of 90.5 % was obtained from the hydrolysis of cellulose catalyzed by the GO/HPW (1:1.5) composites at 115 ℃ for 4 h using catalysts to cellulose 1:1 ratio.

Highly dispersed Ru nanoparticles anchored on NiAl layered double oxides catalyst for selective hydrodeoxygenation of vanillin

The hydrodeoxygenation (HDO) of lignin-derived feedstocks into value-added chemicals with high efficiency and selectivity is desirable for the utilization of biomass resource. The complex oxygen-containing groups of lignin-derived substance result in the challenge of the low selectivity toward the required product. In this work, highly dispersed Ru nanoparticles anchored on Ni3Al1 layered double oxides (LDOs) catalyst derived from NiAl layered double hydroxides (LDHs) with flower-shaped morphology was constructed by a simple deposition-reduction method. The introduction of LDHs-derived support can significantly impact the catalytic activity for the HDO of lignin-derived vanillin (VL) into 2-methoxy-4-methylphenol (MMP). The Ru/Ni3Al1-400 catalyst obtained complete conversion of VL and 94.2% yield of MMP at 130 °C in methanol solvent, much better than the catalysts without LDHs-derived support. The methanol solvent is beneficial for the conversion of reaction intermediate of vanillin alcohol (VA). Detailed characterization reveals that the existence of the enhanced metal-support interaction over Ru/Ni3Al1-400 and the easily accessible acid sites facilitate the production of MMP.

Optimizing the accessibility of zeolite Y on FCC catalyst to improve heavy oil conversion capacity

Optimizing the accessibility of zeolite Y, the main active component in fluid catalytic cracking (FCC) catalyst, is a crucial strategy to improve the heavy oil cracking performance of FCC catalysts. Four FCC catalysts with different Y zeolite content were prepared via in-situ crystallization method by adjusting the crystallization time. The distribution characteristics of the Y zeolite in in-situ crystallized catalysts have been characterized by scanning electron microscopy (SEM), laser confocal fluorescence microscopy and high-resolution field emission scanning electron microscopy (HR-FESEM). A unique structural feature of the FCC catalysts has been achieved, with the Y zeolite component mainly distributing in the outer layer of microspheres. The results of adsorption rate of macromolecule probes reveal that the appropriate zeolite layer thickness and topology were beneficial to the mass transfer performance and acid accessibility of FCC catalyst. The effective utilization ratios of zeolite in the novel FCC catalysts for heavy oil cracking on advanced catalyst equipment (ACE) is in good correspondence with the mass transfer performance of macromolecules and the accessibility of acid sites. It could be confirmed that the excellent heavy oil conversion performance of a FCC catalyst does not depend on the content of zeolite, but rather on the distribution characteristics are in favor of the accessibility of zeolite components.

Ionic liquid supported on mesoporous Pd/SBA-15 during the manufacture of 1,3-butadiene using ethanol at lower temperature reaction

Investigating the heterogeneous organo-catalysts such as 1-Ethyl-3-methylimidazolium trifluoromethanesulfonate upon SBA-15, which includes one percent palladium, and their ability to produce 1,3-butadiene from ethanol while supporting them on mesoporous materials. SBA-15 and metal precursors were mixed together and crushed in solid state. By using the TGA, N2 adsorption–desorption, TEM, and XRD procedures, the produced catalysts were studied. Once an organic motif was added to SBA-15, the solid-state grinding procedure produced more accessible acid sites on the catalyst and increased the dispersion of Pd metal. In a fixed-bed reactor, the catalytic performance was assessed, and a selectivity of up to 82% for 1,3-butadiene was achieved. This is brought on by the coupling activity of Pd and ionic liquid species in the porous structure of SBA-15, where the ionic liquid catalyst promotes ethanol dehydrogenation while Pd promotes aldol condensation The solvent-free method also served as the inspiration for a fresh way of synthesizing catalysts for the formation of 1,3-butadiene using ethanol.