An experimental and theoretical study of glycerol oxidation to 1,3‐dihydroxyacetone over bimetallic Pt‐Bi catalysts

Abstract

It is important to utilize glycerol, the main by‐product of biodiesel, to manufacture value‐added chemicals such as 1,3‐dihydroxyacetone (DHA). In the present work, the performance of five different catalysts (Pt‐Bi/AC, Pt‐Bi/ZSM‐5, Pt/MCM‐41, Pt‐Bi/MCM‐41, and Pt/Bi‐doped‐MCM‐41) was investigated experimentally, where Pt‐Bi/MCM‐41 was found to exhibit the highest DHA yield. To better understand the experimental results and to obtain insight into the reaction mechanism, density functional theory (DFT) computations were conducted to provide energy barriers of elementary steps. Both experimental and calculated results show that for high DHA selectivity, Bi should be located in an adatom‐like configuration Pt, rather than inside Pt. A favorable pathway and catalytic cycle of DHA formation were proposed based on the DFT results. A cooperative effect, between Pt as the primary component and Bi as a promoter, was identified for DHA formation. Both experimental and theoretical considerations demonstrate that Pt‐Bi is efficient to convert glycerol to DHA selectively. © 2016 American Institute of Chemical Engineers AIChE J, 63: 705–715, 2017

Promoting Role of Bismuth on Hydrotalcite-Supported Platinum Catalysts in Aqueous Phase Oxidation of Glycerol to Dihydroxyacetone

“…The selectivity of DHA is comparable to that (ca. 80%) observed on the Pt-Bi supported on carbon-based materials with high BET surface areas [19][20][21][22], in which Bi species were observed in the form of Bi2O2CO3 or Bi2O3 and Bi meal, and the geometric blocking effect of active sites by bismuth adatoms was proposed for the high selectivity of DHA. Owing to the difference in Bi species among the Pt-Bi/HT and Pt-Bi/carbon-based materials, herein, the increase in catalytic activity and selectivity for DHA upon introduction of Bi species could be possibly attributed to the strong hydrogen bond between BiOCl on the surface of HT and glycerol molecule, which enormously enhances the adsorption ability of the catalyst towards glycerol.…”

Navigating Glycerol Conversion Roadmap and Heterogeneous Catalyst Selection Aided by Density Functional Theory: A Review

“…In Section 2.4, Greeley and coworkers [96] modeled Pt-Bi alloys in glycerol oxidation and revealed the working principles of glycerol dehydrogenation in a synchronized manner at the PtO x and Bi sites. Such information is valuable to understand the intrinsic property related to product selectivity, and would be rather elusive to acquire without the aid of molecular modeling.…”

“…Recently, Xiao et al [96] prepared a series of Pt and Pt-Bi catalysts loaded on MCM and ZSM-5 zeolitic supports, such as Pt-Bi/AC, Pt-Bi/ZSM-5, Pt/MCM-41, Pt-Bi/MCM-41, and Pt/Bi-MCM-41. Kinetic measurements showed that bimetallic Pt-Bi loaded on MCM-41 exhibits the highest DHA yield.…”

“…4 Results are taken from Pt(111)/Bi [95], and Pt(100)/Bi with an applied potential of 0.6 V, respectively [95]. 5 Highest DHA selectivity reported during 5 h of experiments [96].…”

“…Supported noble metals, Pt, Pd, and Au, are commonly used [92][93][94][95][96]. Pd/C pH = 11 in air 70 (Glyceric acid) 1 8 (DHA)) [94] Pt/C pH = 7 in air 55 (Glyceric acid) 1 12 (DHA) [94] Pt-Bi/C pH = 11 in air 50 (DHA) 1 [94] Au/AC p O2 (10 bar), 60 • C in NaOH solution 75 (Glyceric acid) 2 15 (Glycolic acid) 2 [92] Pt (111) 1 Selectivity on Pt/C and Pd/C is reported for 90% glycerol conversion, and 70% conversion on Pt-Bi/C.…”