Olefin Hydrogenation Reactions Research Articles

Hydrogenation of Cinnamaldehyde Using Carbon Dots Reduced Palladium Nanoparticles

Carbon dots (CDs) with a size range of 0.2 to 2 nm were prepared using a hydrothermal treatment of sucrose and oleic acid. The as-synthesized CDs were used to reduce H2PdCl4 to metallic Pd nanoparticles with dPd = 9.3 ± 3.7 nm, as confirmed by PXRD and HRTEM data. Pd particles were made to be larger than the CDs, to observe any inverse support effects, however, TEM data revealed that the CDs were transformed to carbon sheets in the reduction reaction at 100 °C. The synthesized Pd-CDs catalysts (0.81 wt. % loading) and CDs were both tested for the liquid phase hydrogenation of cinnamaldehyde. The influence of mass, temperature, and hydrogen flow rate on the activity and selectivity of the CDs and Pd-CDs catalyst on the hydrogenation of cinnamaldehyde was investigated. The CDs gave a cinnamaldehyde conversion (40%, 4 h) with selectivity towards the reduction of the C = O bond (cinnamyl alcohol) while the Pd-carbon catalyst was only selective to the reduction of the C = C bond (conversion 78%) indicating the dominance of Pd in the reaction. Post analysis of the deactivated catalysts indicated formation of carbon sheets and sintering of the Pd nanoparticles. It is thus shown that the presence of Pd induces the CDs to carbon sheet formation and thus indicates the limited use of CDs as a support for the olefin hydrogenation reaction with the CDs produced carbon support. This finding has implications for other studies using CDs as supports.Graphical abstract

Co-Promoted CoNi Bimetallic Nanocatalyst for the Highly Efficient Catalytic Hydrogenation of Olefins

Bimetallic catalysts, especially non-noble metals, hold great potential for substituting for noble metals in catalytic hydrogenation. In present study, a series of CoxNiy (x + y = 6) bimetallic catalysts were prepared through the impregnation–reduction method and cyclohexene was chosen as probe-molecule to study the promotion effect of Co on the catalytic olefin hydrogenation reactions. Meanwhile, density functional theory (DFT) was utilized to investigate the formation energies and the charge distribution of CoNi bimetals, as well as the transition state (TS) searches for hydrogen dissociation and migration. The results suggest that bimetals tend to have superior catalytic performance than pure metals, and Co3Ni3 shows the highest catalytic activity on the cyclohexene hydrogenation. It was found that the charge transfer from Co to Ni and the alloying give rise to the refinement of CoNi grains and the improvement of its catalytic activity and stability. Thus, it may be possible to obtain better catalytic performance by tuning the metal/metal atomic ratio of bimetals.

The nature of “hydrogen spillover”: Site proximity effects and gaseous intermediates in hydrogenation reactions mediated by inhibitor-scavenging mechanisms

Support effects in alkene and arene hydrogenations on metal catalysts attributed to “hydrogen spillover” are shown to reflect the desorption and hydrogenation of Pt-bound intermediates at acid-base pairs on certain oxides (e.g. Al2O3, TiO2, MgO). Toluene-H2 reactions on Pt nanoparticles dispersed on SiO2 (Pt/SiO2) occur on surfaces nearly saturated with a diverse pool of bound species differing in the locations of H-atoms and surface attachments. Their diverse coverages and reactivity cause Pt surfaces to become preferentially occupied by less reactive isomers at the expense of the more competent isomers that account for most hydrogenation turnovers. These less reactive species can desorb from Pt nanoparticles as gaseous methylcyclohexadiene molecules, which diffuse to and react at nearby oxide surfaces; such scavenging increases the relative abundance of the more reactive intermediates at Pt surfaces leading to the rate enhancements inaccurately denoted as “hydrogen spillover.” These rate enhancements become less pronounced as mean inter-function distances between Pt nanoparticles and acid-base pairs on oxide surfaces increase, and as methylcyclohexadiene molecules become less effectively scavenged as their rates of mass transfer become consequential. The Al2O3 surfaces considered here catalyze dihydrogen addition to cyclohexadiene and cyclohexene molecules (but not toluene); titration of acid-base pairs by propanoic acid suppresses such reactions, as well as the significant enhancements of toluene-H2 reaction rates observed when Al2O3 is mixed physically with Pt/SiO2. The rate enhancements conferred by these bifunctional routes represent a natural consequence of the diverse coverage and reactivity of many different species bound on crowded metal surfaces during arene and alkene hydrogenation reactions. Their desorption as partially-hydrogenated molecules enable their scavenging at a second function present within diffusion distances, without requiring inter-function contact or the surface diffusion of H atoms.

Selective hydrogenation of acetylene to ethylene: Performance of a Pt monolayer over an α-WC(0001) surface for binding and hydroconversion of acetylene

Ethylene (C2H4) is a useful hydrocarbon in polymerization reactions and as a probe system to understand hydrogenation reactions of complex unsaturated hydrocarbons and olefins. However, C2H4 streams usually contain small amounts of acetylene (C2H2), which deactivates the catalyst used for ethylene hydroconversions. This issue is overcome by hydrogenating C2H2 selectively into C2H4, avoiding further ethylene hydrogenation reactions. For this process, expensive palladium-based catalysts have shown good performance. Here, based on the results of density functional calculations, we propose the use of cheap and easily available tungsten carbide (WC) as a support of Pt, being an alternative material to Pt-group metals. Clean α-WC(0001)-C and α-WC(0001)-W were compared with Pt-supported on them, i.e. Pt/α-WC(0001)-C and Pt/α-WC(0001)-W. The theoretical results indicate that among the evaluated systems, the Pt/α-WC(0001)-W surface has a remarkable capacity to achieve selective hydrogenation of C2H2 into C2H4, with a reaction energy of -0.44 eV, avoiding further hydrogenation into ethyl (C2H5, +0.29 eV) and ethane (C2H6, +0.33 eV). In Pt/α-WC(0001)-W, the surface poisoning is avoided since ethylidyne (CCH3), a species responsible of catalyst deactivation is not formed. In contrast, the selective acetylene hydrogenation is not feasible on Pt/α-WC(0001)-C, α-WC(0001)-C, and α-WC(0001)-W; these surfaces are all poisoned due to the formation and deposition of CCH3 and C2H2 on them. The atomic charges indicate that the electron density flux from the Pt/α-WC(0001)-W surface to the C2H2 and C2H4 molecules is higher as compared to bare α-WC(0001)-W, since the Pt monolayer modulates electron density migration, as verified by a Projected Density of States (PDOS) analysis. The C2H4 desorption rate from Pt/α-WC(0001)-W is reasonable in the temperature range from 340 to 640 K, providing a theoretical basis for further practical catalysis. The results of this work show that Pt/α-WC(0001)-W is a good candidate for acetylene selective hydrogenation, opening a new window for further experimental and/or theoretical works.

In-Situ upgrading technology: Nanocatalyst concentration levels effects and hydrocarbons paths in the porous medium

The current research work contributes one further step in developing the heavy oil in-situ upgrading technique. The experimental work was carried out using a dolomite corepack as a porous medium at temperature and pressure already investigated in In Situ Upgrading Technology (ISUT). Crude oil was saturated in the corepack to simulate the oil in place in the reservoir; then, hot vacuum residue (VR) plus nanocatalyst, and in the presence of hydrogen (H2) was continuously injected into the porous medium. The nanocatalyst was composed of ultradispersed Ni–Mo and deposited in three incremental steps in the corepack. Depositing catalyst in the corepack aimed to create a reactor in which upgrading reactions can occur. After each incremental nanocatalyst deposition step, the hot VR and H2 continuously flowed at a selected temperature, pressure and residence time through the corepack. The products of every VR plus H2 step were analyzed with techniques such as microcarbon (MCR), simulated distillation (SimDist). The products from the stage with the highest catalyst concentration were determined to have lower VR contents, much lower viscosities, lower sulfur content, and stability; this latter indicating the necessity of carefully controlling processing severity levels. Chemical tracers were added to the crude oil (Phenanthrene) and the VR (1-methylnaphthalene and n-octadecane) at a 1.0 wt% level; their distributions were studied throughout the process via chromatography and mass spectrometry analyses. Cracking, plus olefin and aromatic hydrogenation reactions were evidenced to occur during the ISUT process.

Simulation-assisted design of a catalytic hydrogenation reactor for plastic pyrolysis fuels

An enhancement of the properties of pyrolysis liquids (PL) from municipal plastic waste (mainly low-density polyethylene) by catalytic hydrotreatment is required to obtain automotive quality fuels. In this context, we report the design of a pilot catalytic hydrotreatment reactor using computational fluid dynamics (CFD). This modelling technique considered fluid flows, gas diffusion, olefin hydrogenation reactions, and heat transfer. The built model allowed the development of different sensitive analysis to evaluate the influence of spatial time, heat transfer fluid (used as a reactor coolant) and hydrogen/pyrolysis liquid ratio. Possible phase changes (from gas to liquid) were analyzed by a thermodynamic approach. The results showed that the refrigerant oil allows alleviating possible temperature gradients arising from the exothermic hydrogenation reaction. It was also found that the system can be optimized in order to minimize the energy cost by adjusting the inlet temperature of the reactive gas (H2) and the refrigerant oil flow. Condensations in the reactive chamber could be avoided by working at intermediate pressures (40–60 bar) and/or increasing the feed of H2. Additionally, the results obtained with the CFD 3D model together with the condensation analysis allowed to optimize the operational regime and the pilot-reactor design in terms of dimensioning and construction materials.

Palladium metallated shell layer of shell@core MOFs as an example of an efficient catalyst design strategy for effective olefin hydrogenation reaction

Facile strategies for noble metal dispersion in the shell-layer of core–shell structured metal–organic frameworks based on Zr-MOFs (UiO-66@Pd-UiO-67-BPY) was developed. The robust structure of the core-structure UiO-66 was firstly synthesized before covering up with a shell-structure of UiO-67-BPY obtaining the core–shell structure (UiO-66@UiO-67-BPY). The metallation with active palladium species (PdII) was designed on the shell-layer of core–shell MOFs via a post-synthetic method. The Pd species were coordinated explicitly in a bidentate manner to the bipyridyl linkers of the shell-structure (UiO-67-BPY). Excellent dispersion of Pd in the shell structure was obtained, resulting in UiO-66@Pd-UiO-67-BPY, as confirmed from characterizations. Taking advantage of the designed catalyst, the synthesized UiO-66@Pd-UiO-67-BPY was examined for the catalytic hydrogenation reaction. The results revealed an excellent catalytic performance of UiO-66@Pd-UiO-67-BPY compared with the traditional catalyst Pd-UiO-67-BPY. Moreover, the designed catalyst structure exhibited outstanding performance and paved the way towards a cost-effective catalyst synthesis based on MOFs combined with a noble metal.

Thermodynamic limitations of synthetic fuel production using carbon dioxide: A cleaner methanol-to-gasoline process

Industry generates to the atmosphere greater and greater amounts of CO2harmful to the environment. Its use as a raw material in the production of synthetic fuels realizes the idea of ‘Clean Production’, in which products are made is a sustainable environment conditions. A chemical model was created using an innovative chemical process of CO2and H2synthesis. A thermodynamic analysis of such a process was carried out, determining energy barriers and favourable conditions for its course. This model’s process comprises reactions representing three of its stages :1) synthesis of methanol (METH) and dimethyl ether (DME) with CO2and H2, 2) conversion of the mixture of methanol, ether and water into light olefins and 3) hydrogenation of olefins (C2–C6) to the mixture of paraffins – gasoline. Calculations were made for changes for enthalpy and Gibbs free energy of respective reactions for each stage. The analysis showed that at no stage of the process the level of energy barrier does not exclude (in terms of technology) the possibility of the execution of the process. The equilibrium conversion of CO2within the temperature range (T): = 475–575 K, for p = 1 MPa, and H2/CO2 = 3/1 remains within 20–25%, at products selectivity DME/METH/CO = 0.73/0.14/0.17, at 475 K and 0.0038/0.013/0.98 at 573 K. Olefins are produced in exothermic reactions of DME and METH conversion and the changes in their yield with temperature run through maximum values, which along with increase of carbons in the olefin are shifted towards lower temperatures. Thermal effects (ΔH) of the olefin hydrogenation reaction are similar and are their values range between (−124) and (−137) KJ/mol. Thermodynamic limitations for these reactions no longer exist for temperature <950 K, and their lower conversion at higher temperature can be compensated with increase in pressure (Chatelier’s principle).

Metal Organic Frameworks as Robust Host of Palladium Nanoparticles in Heterogeneous Catalysis: Synthesis, Application, and Prospect.

Metal organic frameworks (MOFs) are one set of the most excellent supports for Pd nanoparticles (NPs). MOFs as the host mainly have the following advantages: (i) they provide size limits for highly dispersed Pd NPs; (ii) fixing Pd NPs is beneficial for separation and reuse, avoiding the loss of expensive metals; (iii) the MOFs skeleton is diversified and functionalized, which is beneficial to enhancing the interaction with Pd NPs and prolonging the service life of the catalyst. This review discusses the synthesis strategy of Pd@MOF, which provides guidance for the synthesis of similar materials. After that, the research advance of Pd@MOF in heterogeneous catalysis is comprehensively summarized, including C-C coupling reaction, benzyl alcohol oxidation reaction, simple olefin hydrogenation reaction, nitroaromatic compound reduction, tandem reaction, and the photocatalysis, with the emphasis in providing a comparison with the performance of other alternative Pd-containing catalysts. In the final section, this review presents the current challenges and which are the next goals in this field.

Enantioselectivity Induced by Stereoselective Interlocking: A Novel Core Motif for Tropos Ligands.

Well‐defined supramolecular interactions are a powerful tool to control the stereochemistry of a catalytic reaction. In this paper, we report a novel core motif for fluxional 2,2′‐biphenyl ligands carrying (S)‐amino acid‐derived interaction sites in 5,5′‐position that cause spontaneous enrichment of the Rax rotamer. The process is based on strong non‐covalent interlocking between interaction sites, which causes diastereoselective formation of a supramolecular ligand dimer, in which the axial chirality of the two subunits is dictated by the stereochemical information in the amino acid residues. The detailed structure of the dimer was elucidated by NMR spectroscopy and single‐crystal X‐ray analysis. Three different phosphorus‐based ligand types, namely a bisphosphine, a bisphosphinite and a phosphoramidite were synthesized and characterized. Whereas the first one was found to exist in a strongly weighted equilibrium, the two others each exhibited stereoconvergent behavior transforming into the diastereopure Rax rotamer. Enriched ligands were used in rhodium‐mediated asymmetric hydrogenation reactions of prochiral olefins in which very high enantioselectivities of up to 96:4 were achieved.

The effect of carrier in KCoMoS-supported catalysts for hydro-upgrading of model FCC gasoline

K-CoMo/Sup (where Sup = Al2O3, SiO2, TiO2 and ZrO2) catalysts were synthesized using H3PMo12O40, CoCO3, KOH and citric acid. The catalysts were characterized by temperature-programmed reduction (TPR), temperature-programmed desorption of NH3, X-ray photoelectron spectroscopy, transmission electron microscopy. Samples were tested in hydrotreating of model fluid catalytic cracking gasoline and in selective hydrogenation of 1,5-hexadiene and n-heptene-1. The type of used carrier significantly affected the morphology of active phase and catalytic properties. Active sites productivity of K-CoMo/Sup catalysts in hydrodesulfurization (HDS) and olefin hydrogenation (HYDO) reactions as well as HDS/HYDO selectivity correlated with active phase morphology excepting TiO2-supported sample. Productivity of active sites in reactions of selective hydrogenation of diolefin depended on maximum peak reduction obtained from TPR, which in turn was a function of acidity of using supports. The highest HDS/HYDO selectivity was obtained at catalyst which possessed the lowest selectivity towards partial hydrogenation of diolefine compared to complete hydrogenation.

Recyclable Magnetic Microporous Organic Polymer (MOP) Encapsulated with Palladium Nanoparticles and Co/C Nanobeads for Hydrogenation Reactions

Microporous organic polymers (MOPs) encapsulated with palladium nanoparticles (NPs) and immobilized on magnetic Co/C nanobeads show excellent activity in hydrogenation reactions of alkenes, alkynes, and nitro arenes with turnover frequencies (TOFs) up to 3000 h–1. The magnetic core of the nanobeads ensures an easy and fast recyclability for at least six consecutive runs by applying an external magnet to recapture the catalyst. The catalytic system reported here uses cross-linked toluene as a polymer structure and is readily prepared via a cost-efficient and versatile synthesis based on commercially available starting materials. The novel catalysts combine the advantages of a heterogeneous magnetic support with MOPs that prevent NPs from agglomeration or deactivation. In addition, the advantages of palladium NPs as exceedingly active catalyst due to their high surface-area-to-volume ratio are exploited. Furthermore, the polymeric structure can easily be varied by the change of the aromatic monomer. Introdu...

New Strategy toward a Dual Functional Nanocatalyst at Ambient Conditions: Influence of the Pd-Co Interface in the Catalytic Activity of Pd@Co Core-Shell Nanoparticles.

Bimetallic nanostructures with a combination of noble and nonnoble metals hold promise for improving catalyst activity and selectivity. Here, we report the synthesis of Pd@Co (PC) core-shell morphology nanoparticles with three different ratios of palladium (Pd) and cobalt (Co), and a possibility to fine tune the ratio of core and shell thickness. PC exhibits superior and selective hydrogenation as well as oxidation catalytic activity at ambient or near-ambient conditions. Various characterization techniques have been employed to confirm the core-shell morphology. Without any pre-treatment or activation, fresh catalysts with different Pd to Co ratios, that is, 2:1, 1:1, and 1:2, were subjected to olefin (phenylacetylene) hydrogenation and oxidation (styrene to styrene oxide) reaction. The catalytic activity results demonstrate that the 1:1 ratio of Pd/Co is the most active composition for controlled and stepwise reduction of phenyl acetylene to styrene and then to ethyl benzene; 1:1 Pd/Co shows 100% styrene conversion in 30 min. with an order of magnitude higher turnover frequency than other catalysts. The 1:1 PC ratio is also the most active composition for selective oxidation of styrene to styrene oxide. NAPXPS (near-ambient pressure XPS) results show that the active sites for catalytic C═C hydrogenation and oxidation reaction are Co0 and Co3+, respectively. However, the superior catalytic performance can be attributed to Co0 (for reduction) or Co3+ (for oxidation), and the Pd-Co interface plays a critical role in stabilizing the required functional character. NAPXPS results confirm that the superior catalytic performance can be attributed not only to Co0 or Co3+, but also to the Pd-Co interface. The electronic effect and synergism between Co and Pd helps Co to stabilize in different oxidation states depending on the reaction conditions, and making it a dual functional catalyst.

Do Olefin Hydrogenation Reactions Remain Structure Insensitive over Pt in Nanostructured Pt-on-Au Catalyst?

Understanding the effects of catalyst surface structure on a catalytic reaction is of fundamental importance in catalysis chemistry. Herein, a series of Pt-on-Au (Ptm^Au, m refers to the atomic Pt/Au ratio; Au size: 3.2 ± 0.4 nm) nanostructures with Pt dispersion in the range of 38% to 100% are used to study the structure sensitivity of the hydrogenation reactions of 1,3-butadiene and ethylene, respectively. The specific catalytic rates for both reactions are observed to increase with a decrease in the Pt dispersion or increasing m in Ptm^Au, demonstrating the structure-sensitive nature of both reactions over the Ptm^Au nanostructures. These observations strongly contrast with the structure insensitivity of the same reactions over our deliberately prepared counterpart Pt/SiO2 catalysts with Pt dispersion varying in 6%∼100% and also those documented in literature and thus identify a distinct feature of Pt in the Ptm^Au nanostructures. Characterization results from XANES spectroscopy and DRIFTS of adsorbed ...

Kinetics and chemoselectivity studies of hydrogenation reactions of alkenes and alkynes catalyzed by (benzoimidazol-2-ylmethyl)amine palladium(II) complexes

A series of (benzoimidazol-2-ylmethyl)amine palladium(II) complexes have been employed as catalysts in the homogeneous hydrogenation of alkenes and alkynes under mild conditions. A correlation between the catalytic activity and the nature of the ligand was established. Kinetic studies of the hydrogenation reactions of styrene established pseudo-first-order dependence on styrene substrate. On the other hand, partial orders with respect to H2 and catalyst concentrations were obtained. The nature of the solvent used influenced the hydrogenation reactions, where coordinating solvents resulted in lower catalytic activities. Kinetics and mechanistic studies performed were consistent with the formation of palladium monohydride intermediates as the active species.

HETEROGEN CATALYSIS IN SUSTAINABLE GREEN SOLVENT: ALKENES HYDROGENATION WITH NEW SILICA IMMOBILIZED PALLADIUM COMPLEX CONTAINING S,O-CHELATING LIGAND

Pd(II) complex containing S,O-chelating ligand was immobilized on surface of the amine functionalized silica support in scCO 2 media. Silica-based catalyst ( SiO 2 -ThiophPd(II)) were characterized by IR, SEM, XRF, and BET analyses. The catalytic activity of the immobilized catalyst in hydrogenation reactions of alkenes has been compared with the homogeneous counterpart. SiO 2 -ThiophPd(II) catalyst showed good activity and reusability than homogeneous system. The best conversion in styrene hydrogenation was obtained with TOF value as 5871 h -1 at 370 K, 10 bar H 2 and 1500 psi total pressure. Especially, while homogeneous counterpart has not activity in cyclohexene hydrogenation, it has been provided 100% cyclohexane conversion with the immobilized catalyst. It has also been found that the catalyst can be reused at least ten times without significant loss of activity in the styrene hydrogenation

Experimental investigation of the role of rock fabric in gas generation and expulsion during thermal maturation: Anhydrous closed-system pyrolysis of a bitumen-rich Eagle Ford Shale

Gold-tube pyrolysis experiments were conducted on miniature core plugs and powdered rock from a bitumen-rich sample of Eagle Ford Shale to investigate the role of rock fabric in gas generation and expulsion during thermal maturation. The samples were isothermally heated at 130, 300, 310, 333, 367, 400, and 425 °C for 72 h under a confining pressure of 68.0 MPa, corresponding to six levels of induced thermal maturity: pre-oil generation (130 °C/72 h), incipient oil/bitumen generation (300 and 310 °C/72 h), early oil generation (333 °C/72 h), peak oil generation (367 °C/72 h), early oil cracking (400 °C/72 h), and late oil cracking (425 °C/72 h). Experimental results show that gas retention coupled with compositional fractionation occurs in the core plug experiments and varies as a function of thermal maturity. During the incipient oil/bitumen generation stage, yields of methane through pentane (C1–C5) from core plugs are significantly lower than those from rock powder, and gases from core plugs are enriched in methane. However, the differences in C1–C5 gas yield and composition decrease throughout the oil generation stage, and by the oil cracking stage no obvious compositional difference in C1–C5 gases exists. The decrease in the effect of rock fabric on gas yield and composition with increasing maturity is the result of an increase in gas expulsion efficiency. Pyrolysis of rock powder yields 4–16 times more CO2 compared to miniature core plugs, with δ13CCO2 values ranging from −2.9‰ to −0.6‰, likely due to carbonate decomposition accelerated by reactions with organic acids. Furthermore, lower yields of gaseous alkenes and H2 from core plug experiments suggest that the rock fabric plays a role in promoting hydrogenation reactions of alkenes.

Reactive Adsorption Desulfurization on Cu/ZnO Adsorbent: Effect of ZnO Polarity Ratio on Selective Hydrogenation

The desulfurization activity and selective hydrogenation of Cu/ZnO adsorbents on the different polarity ratios of ZnO as supports was investigated in reactive adsorption desulfurization. The ZnO particles were synthesized by the hydrothermal process, and CuO/ZnO adsorbents were synthesized by incipient impregnation method. The structure and morphology of the ZnO and CuO/ZnO were characterized by X-ray diffraction (XRD), N2 adsorption–desorption, X-ray photoelectron spectra (XPS), scanning electron microscope/selected area electron diffraction (SEM/SAED), transmission electron microscopy (TEM), and temperature-programmed reduction (TPR). The surface area and polarity ratio of ZnO supports were controlled by the calcination temperature and concentration of P123, respectively. More reactive activity sites were provided by the high surface area of ZnO supports, thus improving the desulfurization activity. The polarity ratio of ZnO may strongly influence the hydrogenation reactions of olefins. The selective hy...

Cooperative Strategies for Catalytic Hydrogenation of Unsaturated Hydrocarbons

This Perspective discusses catalytic hydrogenation reactions of alkenes, alkynes, and other unsaturated C-C substrates in which the catalyst design involves cooperative strategies that enable bifunctional H2 activation and delivery. These approaches complement the more traditional use of single-site precious metal systems for such hydrogenation reactions in homogeneous catalysis. Strategies included in this Perspective are cooperation between (a) a catalytic metal site and a basic ligand residue, (b) a catalytic metal site and an acidic ligand residue, (c) frustrated acid/base pairs, and (d) two co-catalytic metal sites. Unique reactivity and selectivity patterns with non-precious elements that have emerged from successful implementation of these strategies in catalytic transformations are emphasized.

Clay Aerogel Supported Palladium Nanoparticles as Catalysts.

Highly porous, low density palladium nanoparticle/clay aerogel materials have been produced and demonstrated to possess significant catalytic activity for olefin hydrogenation and isomerization reactions at low/ambient pressures. This technology opens up a new route for the production of catalytic materials.