1,3-Butadiene (hereinafter referred to as butadiene), as an important organic intermediate in the chemical industry, has a wide range of uses in the petroleum and rubber industries. Using ethanol as raw material to produce butadiene can solve the non-renewable problem of raw materials, so it has received more and more attention. In this paper, catalysts were hydrothermally synthesized by using SBA-15 as the support, nitrate as the oxide precursor, and nitrogen-containing organic compounds as the additive. And then, the relationship between catalytic performance (ethanol conversion and butadiene yield) and the acid-base properties of catalysts was explored in the synthesis of butadiene from ethanol. Specifically, we used melamine (M), cyanuric acid (Ma), 1,10-phenanthroline (Pm), imidazole (Im), and 1,3,5-triazine (St) as nitrogen-containing additives for the preparation of Zn-Zr/SBA-15+X catalysts. Through the activity evaluation of the catalysts, the activities of ethanol dehydrogenation and dehydration, acetaldehyde condensation, and Meerwein-Ponndorf-Verley (MPV) reactions were calculated. Then, by analyzing the dependence of these activities and butadiene yield on the acidity and basicity (the strength and number of acidic/basic sites) of catalysts, we found that appropriate amounts of weak acid (0.022 mmol center dot g(-1)), moderate acid (0.078 mmol center dot g(-1)), moderate base (0.055 mmol center dot g(-1)), and strong base (0.056 mmol center dot g(-1)) are helpful for the ethanol dehydrogenation, whereas excess amount of weak acid and moderate acid will lead to the ethanol dehydration. Appropriate amounts of moderate acid (0.078 mmol center dot g(-1)) and moderate base (0.055 mmol center dot g(-1)) will favor the acetaldehyde condensation and MPV reactions. The butadiene yield is closely related to the activities of acetaldehyde condensation and MPV. The melamine-modified catalyst (Zn-Zr/SBA-15+M) has the optimum amounts of weak acid, moderate acid, moderate base, and strong base in accordance with the above quantities, resulting in the best catalytic performance: 99.5% conversion of ethanol, 65.5% selectivity of butadiene, and 0.45 gBD center dot g(cat)(-1)center dot h(-1) of butadiene productivity.

As a sustainable, environmentally friendly, and economically viable way to produce 1,3-butadiene, the ethanol-to-butadiene (ETB) process has received increasing attention recently. This ETB process normally requires catalysts with suitable acidity and basicity, namely an acid-base balance. However, the origin of acid-base balance has not yet been elucidated. Herein, we demonstrate that by finely coordinating the interaction of ZnO and ZrO2, a butadiene productivity of 0.33 g(BD) g(cat)(-1) h(-1) at low WHSV and 1.39 gBD g(cat)(-1) h(-1) at high WHSV can be achieved. In contrast, pure ZnO prefers ethanol dehydrogenation to acetaldehyde and pure ZrO2 favors ethanol dehydration to ethylene and diethyl ether. Through a variety of characterization techniques, we found that the interaction of ZnO and ZrO2 alters the acidity and basicity of catalysts, resulting in volcanic shapes of ethanol conversion, butadiene selectivity, and butadiene yield in the ETB process. These findings provide in-depth insights into the understanding of the ETB process and may also apply to other reaction systems using ZnO-ZrO2 as catalytically active components.

The upgrading of ethanol to produce n-butanol and other >C-4 alcohols is a promising reaction. However, the development of efficient catalysts for this reaction has been slow. In this study, we prepared a series of Pd@UiO66-X catalysts using ligands functionalized with electron-donating groups (-NH2 and -CH3) and electronaccepting groups (-H and -NO2). These functional groups play two roles in mediating the microenvironment of the Pd metal. Firstly, they regulate the electronic properties of the Pd metal, and secondly, they alter the hydrophilicity/hydrophobicity surrounding the Pd metal. The intrinsic electronic properties of the Pd metal significantly influence ethanol conversion, while the hydrophilicity/hydrophobicity surrounding the Pd metal is an extrinsic factor. As a result, the Pd@UiO-66-CH(3 )catalyst with a hydrophobic microenvironment around the electron-rich Pd metal exhibits the highest ethanol conversion and n-butanol yield among all the Pd@UiO-66-X catalysts. It also achieves an impressive >C-4 alcohols yield of up to 47.7 %, which is the highest reported to date.

As a sustainable, environmentally friendly, and economically viable way to produce 1,3-butadiene, the Ethanol-to-Butadiene process has received increasing attention recently. This process normally requires catalysts with proper acidity and basicity, namely an acid-base balance. However, the origin of acid-base balance has not yet been elucidated. Here, we demonstrate that an intimate interaction of ZnO and ZrO2 over ZnO-ZrO2 catalysts not only facilitates a formation of a ZnO-on-ZrO2 stacking structure with ZnO in an amorphous state, but also gives rise to a variation of acid/base properties of catalysts, which can be directly and quantitatively correlated to the catalytic performance of catalysts in the Ethanol-to-Butadiene process. These findings provide in-depth insights into the understanding of acid-base balance for the Ethanol-to-Butadiene process, and may also apply to other reaction systems using ZnO-ZrO2 as catalytic active components.