Lewis acidic zeolites are rapidly emerging liquid-phase Lewis acid catalysts. Nevertheless, their inefficient synthesis procedure currently prohibits greater utilization and exploitation of these promising materials. Herein, we demonstrate that SnIV-containing zeolite beta can readily be prepared both selectively and extremely rapidly by solid-state incorporation (SSI) method. Through a combination of spectroscopic (XRD, UV/Vis, X-ray absorption, magic-angle spinning NMR, and diffuse reflectance infrared Fourier transform spectroscopy) studies, we unambiguously demonstrate that site-isolated, isomorphously substituted SnIV sites dominate the Sn population up to a loading of 5 wt % Sn. These sites are identical to those found in conventionally prepared Sn-beta, and result in our SSI material exhibiting identical levels of intrinsic activity (that is, turnover frequency) despite the threefold increase in Sn loading, and the extremely rapid and benign nature of our preparation methodology. We also identify the presence of spectator sites, in the form of SnIV oligomers, at higher levels of Sn loading. The consequences of this mixed population with regards to catalysis (Meerwein–Pondorf–Verley reaction and glucose isomerization) are also identified.
Hierarchical stannosilicates with BEA framework topology are found to catalyze the conversion of bulky ketone substrates, and demonstrate exceptional stability in the continuous regime.
Bifunctional Sn- and Al-containing BEA zeolites, prepared by solid state incorporation, allow furanic ethers to be produced continuously at high (>80%) levels of selectivity.
The need for sustainable energy sources is now more urgent than ever, and hydrogen is significant in the future of energy. However, several obstacles remain in the way of widespread hydrogen use, most of which are related to transport and storage. Dilute formic acid (FA) is recognized asa a safe fuel for low-temperature fuel cells. This review examines FA as a potential hydrogen storage molecule that can be dehydrogenated to yield highly pure hydrogen (H2) and carbon dioxide (CO2) with very little carbon monoxide (CO) gas produced via nanoheterogeneous catalysts. It also present the use of Au and Pd as nanoheterogeneous catalysts for formic acid liquid phase decomposition, focusing on the influence of noble metals in monometallic, bimetallic, and trimetallic compositions on the catalytic dehydrogenation of FA under mild temperatures (20–50 °C). The review shows that FA production from CO2 without a base by direct catalytic carbon dioxide hydrogenation is far more sustainable than existing techniques. Finally, using FA as an energy carrier to selectively release hydrogen for fuel cell power generation appears to be a potential technique.
Monometallic Au and Pd, and bimetallic AuxPdy (x/y mole ratio Au/Pd: 3 : 1, 1 : 1 and 1 : 3) catalysts supported on reduced graphene oxide (rGO) have been synthesised by the sol-immobilization method.
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