Direct Conversion of Bio-ethanol to Isobutene on Nanosized Zn_xZr_yO_z Mixed Oxides with Balanced Acid–Base Sites

Abstract

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.

Synthesis of 1,3-Diols from Isobutene and HCHO via Prins Condensation-Hydrolysis Using CeO2 Catalysts: Effects of Crystal Plane and Oxygen Vacancy

“…For example, dehydration of 3-methyl-1,3-butanediol produces isoprene [3], which is mainly used as a monomer for manufacture of polyisoprene rubber and butyl rubber [4,5]. 3-methyl-1,3-butanediol can be synthesized by Prins condensation of isobutene with formaldehyde to 4,4-dimethyl-1,3-dioxane followed by its hydrolysis [6], which is a promising route because the feedstocks (isobutene [7][8][9] and formaldehyde [10,11]) can be found in bio-refineries, based on recent research and industrial progress [12][13][14]. In the synthesis route, both the Prins condensation and hydrolysis reaction require acid catalysts [3,15,16].…”

Supported Hybrid Enzyme-Organocatalysts for Upgrading the Carbon Content of Alcohols

“…This can be accomplished by deoxygenating and coupling individual molecules into an oligomer. This task has been performed using various approaches, most of them involving energy-intensive processes such as heating the alcohol at high temperatures in presence of suitable catalysts (4)(5)(6). However, it would be desirable to perform these conversions with as little thermal input as possible.…”

Carbon-Carbon Bond Forming Reactions Over Metal Oxide Catalysts

“…The industrially-relevant molecule 2-methylpropene has also been produced from ethanol through a similar proposed aldol intermediate [56]. In this reaction, ethanol is fed to the reactor along with water, which probably facilitates the C-C bond breaking of the aldol products [56].…”

“…In this reaction, ethanol is fed to the reactor along with water, which probably facilitates the C-C bond breaking of the aldol products [56].…”

“…Each of these individual steps, ethanol to 2-propanone [57][58][59][60][61] and 2-propanone to 2-methylpropene [41,62] have been explored, but only recently has the concerted reaction been completed over a Zn/Zr oxide catalyst [56]. As described earlier, a catalyst with appropriately weak acid sites is necessary, being careful to avoid the dehydration of ethanol to the undesired product ethene.…”