We report the design and synthesis of nanosized Zn(x)Zr(y)O(z) mixed oxides for direct and high-yield conversion of bio-ethanol to isobutene (~83%). ZnO is addded to ZrO(2) to selectively passivate zirconia's strong Lewis acidic sites and weaken Brönsted acidic sites, while simultaneously introducing basicity. As a result, the undesired reactions of bio-ethanol dehydration and acetone polymerization/coking are suppressed. Instead, a surface basic site-catalyzed ethanol dehydrogenation to acetaldehyde, acetaldehyde to acetone conversion via a complex pathway including aldol-condensation/dehydrogenation, and a Brönsted acidic site-catalyzed acetone-to-isobutene reaction pathway dominates on the nanosized Zn(x)Zr(y)O(z) mixed oxide catalyst, leading to a highly selective process for direct conversion of bio-ethanol to isobutene.
Preferential growth of MgO(111) nanosheets with a thickness typically between 3 and 5 nm (see TEM image) has been achieved by a simple, efficient, and inexpensive wet chemical route. The MgO(111) nanosheets have been shown to have ultrahigh activity for the Claisen–Schmidt condensation of benzaldehyde and acetophenone.
Three-dimensional porous chromium oxide single crystals have been prepared by aminosilylation of the surface silanols of the template, SBA-15, anchoring of dichromic acid to the grafted amine groups, thermal decomposition of inorganic and organic compounds, and removal of the silica framework with HF.
MgO(111) nanosheets can be prepared via a facile wet chemical process. The MgO(111) nanosheets possessing
the exposed (111) plane as a main surface have a thickness typically between 3 and 5 nm. Study of MgO(111)
nanosheets by in situ diffuse reflectance Fourier transform (DRIFT) spectroscopy suggests that hydroxyl
groups, oxygen vacancies, and surface oxygen anions exist on the surface and the (111) surface may be
stabilized by hydroxyl groups. DRIFTS and temperature-programmed desorption (TPD) studies of CO2
adsorption reveal that there are large amounts of medium basic sites which can be attributed to the high
concentration of surface O2- Lewis basic sites. DRIFTS and temperature-programmed reaction studies (TPRS)
of methanol have demonstrated that, in contrast to commercial MgO, MgO(111) nanosheets are highly reactive
toward the decomposition of methanol. Methanol can be decomposed and the surface CO species formed
can be oxidized readily at low temperature by the high concentration of oxygen anions on the surface of
MgO(111) nanosheets, which demonstrates that these nanosheets have potential application in fuel cells and
methanol-based alternative energy technologies.
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