Heterogeneous catalysts have been a central element in the efficient conversion of fossil resources to fuels and chemicals, but their role in biomass utilization is more ambiguous. Zeolites constitute a promising class of heterogeneous catalysts and developments in recent years have demonstrated their potential to find broad use in the conversion of biomass. In this perspective we review and discuss the developments that have taken place in the field of biomass conversion using zeolites. Emphasis is put on the conversion of lignocellulosic material to fuels using conventional zeolites as well as conversion of sugars using Lewis acidic zeolites to produce useful chemicals.

The small-pore pure silica zeolite ITQ-12 has been synthesized with fumed silica as the silica source in the presence of 1,3,4-trimethylimidazolium hydroxide and hydrofluoric acid under hydrothermal conditions at 448 K. Rietveld refinement using synchrotron X-ray diffraction data of the calcined ITQ-12 product taken at 298 K confirms the proposed topology, framework type code ITW, which can be described by a monoclinic unit cell [Si(24)O(48)] having Cm symmetry. Unit cell parameters are a = 10.3360(4), b = 15.0177(6), and c = 8.8639(4) A, beta = 105.356(3) degrees, and cell volume V = 1326.76(9) A(3). For as-synthesized ITQ-12, the occluded fluoride anion is located inside the double four-membered ring, while the flat 1,3,4-trimethylimidazolium cation lies on the equatorial plane of the slit-shaped [4(4)5(4)6(4)8(4)] cage, with its longest dimension in the [010] direction. The monoclinic unit cell |(C(6)N(2)H(11))(+)(2)F(-)(2)|[Si(24)O(48)], having Cm symmetry, has parameters a = 10.4478(3), b = 14.9854(4), and c = 8.8366(3) A, beta = 105.935(2) degrees, and cell volume V = 1330.34(7) A(3) at 298 K. Cooperative structure-directing effects during the crystallization of ITQ-12 are discussed in terms of the structure of the as-made material.

A study of the adsorption properties of the new, 8-ring, pure silica zeolite ITQ-12 at several temperatures reveals that it has unique, temperature dependent adsorption selectivity and high potential for the separation of propene from propene/propane mixtures. At 30 °C, propene is adsorbed more than 100 times faster than propane, forming the basis for a kinetic based separation. Unexpectedly, at 80 °C, little or no propane adsorption is observed whereas there is no evidence for any unusual decrease in propene adsorption, a property adding to the potential of this zeolite for propene separation. A small, temperature induced decrease in the minimum dimension of the ITQ-12's “slit shaped” cages is proposed as the reason for the loss of sorption capacity for the slightly larger propane molecules. ITQ-12's unique, temperature-dependent property gives rise to a sorption selectivity that is thermodynamically driven rather than the result of diffusion barriers. Preliminary PSA simulations indicate 99.5% purity propene can be achieved with productivity significantly larger than that reported for the aluminophosphate based zeolite, AlPO-14.

are more convenient and secure to be transported and stored. However, the conversion efficiencies of these AORs are commonly inferior to hydrogen oxidation. This is partially due to the sluggish kinetics of multielectrons' transferred processes inside alcohols (e.g., methanol, ethanol, ethylene glycol, and glycerol). [7][8][9][10][11] In this regard, various catalysts of both noble and non-noble metals have been designed and synthesized to boost such sluggish AORs. Although noble metal catalysts (e.g., Pd, Pt, and Rh) are more expensive than non-noble metals (e.g., Ni, Co, and Mn), their more negative AOR onset potentials make them superior for the construction of DAFCs, [4,5,11] originating from their unique electronic structures. Among reported noble-based catalysts, those based on the Pt metal are regarded as the star electrocatalysts for the AORs in terms of their oxidation overpotentials and Tafel slopes. [12,13] Notably, their alloys with other metals (e.g., Ru, Ni, Co, Pd, Rh, and Au) exhibit strong adsorption capability toward OH species or a so-called bifunctional mechanism, leading to improved AOR performance. [14][15][16][17] On the other hand, the serious poisoning effect of the carbonaceous intermediates (especially CO) hinders dramatically the activity of the used catalysts (especially the Pt catalysts) and eventually leads to much reduced conversion efficiencies of the AORs. [18,19] In this context, the screwlike PdPt alloy nanowires [19] and PdPt alloy nanoparticles [20] have been employed to replace single metallic Pt catalysts for methanol electro-oxidation reaction (MOR). Originating from varied electronic structures that are induced by the addition of Pd atoms, these PdPt alloys have been confirmed as commendable MOR catalysts. Although the sizes and compositions of these catalysts have been tuned and the AOR performance on these catalysts has been explored, the performance of these bimetallic heterostructures/catalysts is still far away for their commercial applications. The catalysts featuring superior AOR performance over those reported are still highly demanded for the construction of high-performance DAFCs.It has been well known that the optimization of these noble-metallic heterostructures/catalysts with respect to their morphologies and exposed facets is helpful to enhance their catalytic performance. [21][22][23][24] Among various heterostructures, a catalyst with a core-shell structure has been attracted special attention. [25][26][27][28][29][30] Its structure and its catalytic activity of the shell are revealed to be highly dependent on the used core. [31][32][33][34] This is because the strain effect (expansion or compression) can be Direct alcohol fuel cells (DAFCs) utilize alcohol electro-oxidation reactions (AORs) to provide electricity, where catalysts with optimal electronic structures are required to accelerate sluggish AORs. Herein, an electrocatalyst with an Au-nanorod core and a PdPt-alloy shell is designed. Its electronic structures are modulated through epitaxial growth ...

sive utilization of fossil fuels. The design and development of efficient, economic, and sustainable strategies to convert clean energy (e.g., solar energy, wind energy, and hydropower energy) is thus of great significance. Among various available strategies, electrochemical energy conversion technologies have been attracted extreme attention. They mainly include (photo)electrochemical reduction of atmosphere-rich and greenhouse gas-carbon dioxideinto high value-added chemicals or liquid fuels under mild reaction conditions, electrosynthesis of NH 3 with low energy consumption to substitute the Haber method, electrochemical overall water splitting, and different kinds of fuel cells. By use of these electrochemical energy conversion technologies, it is believed that both the issues of energy shortage and environmental pollution are promising to be solved, eventually creating a globalized system with a sustainable energy circle for our society in the future (Figure 1). [1][2][3][4][5][6][7] To achieve efficient electrochemical conversion technologies, high-performance electrochemical conversion platforms need to be initialized, where electrocatalysts are frequently required. An electrocatalyst actually plays a vital role in the determination and further improvement of reaction rate, efficiency, and selectivity of different electrochemical transformations. In terms of its catalytic performance, the most crucial factors are generally considered as the amount of its active sites, the intrinsic activity of each active site, and the total efficiency of these active sites. [8] It is well-known that the amount of active sites of an electrocatalyst and its electrocatalytic efficiency can be increased through enlarging the surface area of an electrocatalyst, for example by means of synthesizing a nanostructured catalyst (e.g., nanosheets, [9] nanowires, [10] nanopores, [11][12][13] and coreshell structures [14,15] ). Meanwhile, the intrinsic activity of each catalytic site basically follows the Sabatier principle, [16][17][18][19][20] which is closely related to the ability of an electrocatalyst to weaken or strengthen the binding energies with reactants, reaction intermediates, and/or products. For example, when the free energy of hydrogen adsorption (ΔG H ) on the active sites of an electrocatalyst remains at a moderate strength, this catalyst exhibits the highest catalytic activity toward hydrogen evolution reaction (HER). In contrast, too strong or too weak ΔG H on the active sites of an electrocatalyst precludes the HER. [21][22][23] Among numerous electrocatalysts, multiple metal components based electrocatalysts have been extensively utilized in Strain engineering of nanomaterials, namely, designing, tuning, or controlling surface strains of nanomaterials is an effective strategy to achieve outstanding performance in different nanomaterials for their various applications. This article summarizes recent progress and achievements in the development of strain-rich electrocatalysts (SREs) and their applications in the fi...

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a direct alkaline ethanol fuel cell owns more advantages. [4-6] For example, the production of ethanol from biomass is nonpoisonous and convenient. Ethanol is safe to be stored. More importantly, ethanol can be directly oxidized into CO 2 in an alkaline medium. [7,8] This complete ethanol oxidation reaction (EOR) involves the transfer of 12 electrons (Equation (1)), leading to a much higher energy density (e.g., 6.34 kWh L −1 for ethanol). Unfortunately, this EOR is kinetically sluggish in that the stable CC bond in ethanol molecules has to be broken. Given this fact, ethanol is much easier to be oxidized into acetate rather than CO 2. This oxidation pathway delivers only 4 electrons (Equation (2)). Based on the numbers of carbon atoms in the products and electrons transferred per ethanol molecule, these EOR pathways are termed as C1-12e and C2-4e, respectively. [7-10] In terms of energy density of the EOR, the C2-4e pathway has a three times lower efficiency than that of the C1-12e one. To improve the energy efficiency of direct ethanol fuel cells, advanced electrocatalysts that favor the C1-12e EOR pathway are thus are highly pursued.

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