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Zeolites are widely used in petrochemical processes and refineries due to their well‐ordered microporous network and large surface area. However, the diffusion of reactants and products is hampered by the narrow microporous channels, causing limitations. To overcome this challenge, modifying the pore structure is crucial, and the chemical etching technique is a powerful tool that introduces mesopores and macropores, consequently enhancing mass transfer and accessibility. Diverse chemical etching methods have been invented, including exposure to both acids (organic/inorganic acids), alkali (organic/inorganic alkali), and neutral etchants (e. g., ammonium fluoride). This review summarizes and assesses the chemical etching methods and their relevance to catalytic cracking reactions, methanol to hydrocarbons (MTH), and biomass conversion. The potential of zeolites with modified pore structures has motivated researchers to develop novel methods to tackle the practical challenges associated with their applications. [ABSTRACT FROM AUTHOR]

Abstract: [Bis(imidazolyl)–BH2]+[bis(triazolyl)–BH2]− and [bis(imidazolyl)–BH2]+[tris(triazolyl)–BH]− were synthesized, the cations and anions of which were functionalized with B−H groups and azoles. As B−H groups contribute to the hypergolic activity and azole groups improve the energy output, the resulting ionic liquids exhibited ignition delay times as low as 20 ms and energy outputs as high as 461.1 kJ mol−1. In addition, densities (1.07–1.22 g cm−3) and density‐specific impulse (≈360 s g cm−3) values reached a relatively high level. These ionic liquids show great promise as sustainable rocket fuels. [ABSTRACT FROM AUTHOR]

A series of hypergolic salts based on [B12H11NH3]− anion were synthesized. The resulting six salts were characterized by 1H and 13C NMR, IR, ESI-MS and EA. Their key properties were measured or calculated, including melting points (133.9–210.7 °C), decomposition temperatures (215.6–278.2 °C), and heats of formation (−40.1 to 1073.0 J g−1). As expected, the [B12H11NH3]− salts (1–6) possess higher specific impulses (274.9–276.8 s) than the corresponding [B12H12]2− salts (269.8–272.6 s). When the fuel/oxidizer combinations range from 20% to 50%, specific impulse values of the salts are still maintained at a high level of above 269 s. [ABSTRACT FROM AUTHOR]

In hypergolic propellants, hypergolicity is an extremely important parameter in evaluating fuels. In this study, a new family of hypergolic metal (Cu2+, Ni2+, Zn2+) complexes with B12H122- were synthesized and fully characterized. Two of these six complexes exhibited ultrashort ignition delay times (ca. 1 ms), with white fuming nitric acid as the oxidizer, besides good physicochemical properties (decomposition temperatures: 221.8--286.3 °C; densities: 1.215--1.264 g cm-3). The results demonstrate their promising applications in bipropellant formulations. [ABSTRACT FROM AUTHOR]

[Bis(imidazolyl)-BH 2 ] + [bis(triazolyl)-BH 2 ] - and [bis(imidazolyl)-BH 2 ] + [tris(triazolyl)-BH] - were synthesized, the cations and anions of which were functionalized with B-H groups and azoles. As B-H groups contribute to the hypergolic activity and azole groups improve the energy output, the resulting ionic liquids exhibited ignition delay times as low as 20 ms and energy outputs as high as 461.1 kJ mol -1 . In addition, densities (1.07-1.22 g cm -3 ) and density-specific impulse (≈360 s g cm -3 ) values reached a relatively high level. These ionic liquids show great promise as sustainable rocket fuels., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)