Catalyst Stability Assessment in a Lab-Scale Liquid-Solid (LS)² Plug-Flow Reactor

Abstract

A packed-bed plug-flow reactor, denoted as the lab-scale liquid-solid (LS)² reactor, has been developed for the assessment of heterogeneous catalyst deactivation in liquid-phase reactions. The possibility to measure intrinsic kinetics was first verified with the model transesterification of ethyl acetate with methanol, catalyzed by the stable commercial resin Lewatit K2629, for which a turnover frequency (TOF) of 6.2 ± 0.4 × 10−3 s−1 was obtained. The absence of temperature and concentration gradients was verified with correlations and experimental tests. The potential for assessing the deactivation of a catalyst was demonstrated by a second intrinsic kinetics evaluation where a methylaminopropyl (MAP)-functionalized mesoporous silica catalyst was used for the aldol reaction of acetone with 4-nitrobenzaldehyde in different solvents. The cooperative MAP catalyst deactivated as a function of time on stream when using hexane as solvent. Yet, the monofunctional MAP catalyst exhibited stable activity for at least 4 h on stream, which resulted in a TOF of 1.2 ± 0.1 × 10−3 s−1. It did, however, deactivate with dry acetone or DMSO as solvent due to the formation of site-blocking species. This deactivation was mitigated by co-feeding 2 wt % of water to DMSO, resulting in stable catalyst activity.

Catalytic Oxidation of Toluene into Benzaldehyde and Benzyl Alcohol Using Molybdenum-Incorporated Manganese Oxide Nanomaterials

“…The turnover frequency (TOF) of the different cycles is measured from the slope of the time versus conversion graphs of individual cycles. 31 The percent toluene conversion and turnover frequencies obtained after 18 h of catalytic activity cycles are enlisted in Table 6 and TOF trends are depicted in Figure 9. The TOFs calculated for successive activity cycles were 1.94, 1.43, 1.39, 1.32, 1.11, and 1.01 s −1 , respectively.…”

Perspective on Overcoming Scale-Up Hurdles for the Reductive Catalytic Fractionation of Lignocellulose Biomass

“…However, care should be taken to avoid downstream phase separation due to heat losses, e.g. , via heat tracing of the lines. , On an industrial scale, insulating the transport piping will most likely be preferred due to the high operating costs related to additional heating of piping.…”

A Pyrrolidine Functionalized Poly[(ethylene glycol) Methacrylate] Resin as a Heterogeneous Catalyst for Aqueous Aldol Reactions

“…In an aqueous environment, however, silica and organosilica supports exhibit poor stability as their siloxane bonds are prone to hydrolysis, causing structural degradation and leaching of active sites [1,19,23].…”