Structural Evolution of MOF-Derived RuCo, A General Catalyst for the Guerbet Reaction

Abstract

Guerbet alcohols, a class of β-branched terminal alcohols, find widespread application because of their low melting points and excellent fluidity. Because of the limitations in the activity and selectivity of existing Guerbet catalysts, Guerbet alcohols are not currently produced via the Guerbet reaction but via hydroformylation of oil-derived alkenes followed by aldol condensation. In pursuit of a one-step synthesis of Guerbet alcohols from simple linear alcohol precursors, we show that MOF-derived RuCo alloys achieve over a million turnovers in the Guerbet reaction of 1-propanol, 1-butanol, and 1-pentanol. The active catalyst is formed in situ from ruthenium-impregnated metal–organic framework MFU-1. XPS and XAS studies indicate that the precatalyst is composed of Ru precursor trapped inside the MOF pores with no change in the oxidation state or coordination environment of Ru upon MOF incorporation. The significantly higher reactivity of Ru-impregnated MOF versus a physical mixture of Ru precursor and MOF suggests that the MOF plays an important role in templating the formation of the active catalyst and/or its stabilization. XPS reveals partial reduction of both ruthenium and MOF-derived cobalt under the Guerbet reaction conditions, and TEM/EDX imaging shows that Ru is decorated on the edges of dense nanoparticles, as well as thin nanoplates of CoO x . The use of ethanol rather than higher alcohols as a substrate results in lower turnover frequencies, and RuCo recovered from ethanol upgrading lacks nanostructures with plate-like morphology and does not exhibit Ru-enrichment on the surface and edge sites. Notably, 1H and 31P NMR studies show that through use of K3PO4 as a base promoter in the RuCo-catalyzed alcohol upgrading, the formation of carboxylate salts, a common side product in the Guerbet reaction, was effectively eliminated.

Enhanced Conversion of Ethanol into n-Butanol over NiCeO2@CNTs Catalysts with Pore Enrichment Effects

“…Condensation of acetaldehyde is the other key step in the ethanol to n -butanol conversion process, which is determined by the acid and base sites of the catalysts. , To disclose the in-depth reason for the high n -butanol selectivity, the acid–base sites of NiCeO 2 /CNTs and NiCeO 2 @CNTs catalysts were characterized by NH 3 -TPD and CO 2 -TPD. As shown in Figure A, two peaks located at 370 and 667 K were observed for NiCeO 2 @CNTs catalysts, which were ascribed to the NH 3 desorption and decomposition of surface functional groups on CNTs, respectively, as evidenced by the online MS in Figure B.…”

Scent of knowledge: The molecular fingerprint of volatiles in an emblematic historical library in Italy

“…The presence of alcohols such as heptanol and 2‐ethyl‐1‐hexanol among VOCs from naturally aged paper was already mentioned; 7,8,12,15 the former develops during autoxidation of fatty acids, 4,7,8,11–15 while the latter was considered a decomposition marker of cellulose 12 but its formation as a result of a degradation pathway was never clarified; it is here hypothesized for the first time that its synthesis may be the result of a Guerbet reaction that converts a primary alcohol into its β‐alkylated dimer with loss of one equivalent of water. This way, butanol, which can easily be provided by the acetone‐butanol‐ethanol biochemical conversion of sugars, might be converted into 2‐ethyl‐1‐hexanol 37,38 and the chirality of the found 2‐ethyl‐1‐hexanol lends support to its relationship with paper biodegradation pathways 12 . Alcohols such as heptanol and 2‐ethyl‐1‐hexanol contribute to a green and sweet odor even if their odor threshold is higher than their corresponding aldehyde 36 …”

Synthesis of Isocyanurate-Imidazolium-Derived Flexible Ionic Porous Organic Polymers for CO2 Fixation

“…The isocyanurate-imidazolium-derived iPOPs (IC-IM-1, IC-IM-2, and IC-IM-3) are synthesized via Heck cross-coupling reaction of the tri(4-ethenylbenzene)isocyanurate (IC) with the substituted imidazolium salts (IM-1, IM-2, and IM-3) in the presence of tetrakis(triphenylphosphine)palladium in high yields (82−85%). The as-obtained IC-IMs are characterized by Fourier transform infrared (FTIR) spectroscopy, by solidstate 13 C NMR spectroscopy, and by X-ray photoelectron spectroscopy (XPS). As shown in the FTIR spectra of obtained iPOPs (Figure 1a), the peaks at the region of 1694−1701 cm −1 belong to stretching vibration of C�O.…”

“…12 However, homogeneous IL catalysts are difficult to be recycled from the catalytic reaction system, which has been an obstacle for them to be applicable. 13 Thus, it is of great interest to design high-performance IL-derived heterogeneous catalysts for the CO 2 fixation and conversion.…”