The hydrogenation of isophorone to trimethyl cyclohexanone using the downflow single capillary reactor

Despite many innovations in the intensification of catalytic multiphase reactors for the small and medium scale manufacture of chemicals, there have as yet been relatively few commercial successes. One reason for this might be that many of these developments inherently incorporate a fixed catalyst, which may not suit an industry that is based on principles of batch manufacture and multi-product plant. This study evaluates an intensified reactor that encompasses the opportunities demonstrated from structured flows and thin channels, together with a mobile, slurry catalyst, namely a capillary reactor with gas/liquid/suspended catalyst flow. A downflow single capillary reactor (SCR) was designed, built and evaluated for the selective hydrogenation of isophorone to trimethyl cyclohexanone using commercial Pd- and Rh-based catalysts. Using the single capillary arrangement, the reaction was shown to be operating under kinetic control. Comparison of the rate of hydrogenation with autoclave showed a significant increase of the reaction rate when capillary reactor was used. The temperature of reaction is a crucial factor in tuning the reaction towards different products. The constant relative reaction rate obtained for different catalyst loading as well as the calculated value of the apparent activation energy show that the reaction of hydrogenation of isophorone is not mass transfer limited in the single capillary reactor. © 2005 Elsevier B.V. All rights reserved

FLT3-ITD DNA allelic burden, but not mRNA levels, influences the biological characteristics of AML patients

FMS-like tyrosine kinase 3 gene internal tandem (FLT3-ITD) mutations represent one of the most frequent genetic lesions in acute myeloid leukemia (AML) and imparts a negative prognostic. For an optimal patient management, current clinical guidelines recommend the evaluation of the allelic ratio (AR), expressed as the DNA FLT3-ITD/WT mutational burden. We sought to evaluate the differences between the AR and FLT3-ITD/WT mRNA ratio (RR) and their respective impact on the biological characteristics of AML patients. A total of 32 DNA and mRNA samples from AML patients with FLT3-ITD were evaluated. There was a good correlation between the AR and RR (Spearman’s rho= 0.652, P <0.001). None of the biological characteristics were influenced by the RR values, whereas patients with high AR values (≥0.5) had higher WBC counts (Mann-Whitney, P= 0.01), LDH levels (Mann-Whitney, P= 0.037), and circulating blasts levels (Mann-Whitney, P= 0.023) than patients with low AR values (<0.5). Also, there was a good correlation between AR values and WBC count (Spearman’s correlation, P= 0.001), and LDH levels (Spearman’s correlation, P= 0.007). In our study population the AR, but not the RR, influenced the biological characteristic of patients suggesting a dose-independent effect of FLT3-ITD mutations

Intensification of the solvent-free catalytic hydroformylation of cyclododecatriene: Comparison of a stirred batch reactor and a heat-exchange reactor

The potential of heat-exchange reactors with mm-scale channels to provide process intensification for homogeneously catalysed gas-liquid reactions was explored. The solvent-free hydroformylation of cyclododecatriene using a homogeneous catalyst was carried out in a heat-exchange (HEx) reactor with mm-scale thin channels, and in a stirred batch autoclave for comparative purposes. The reaction was carried out using generally a concentration of 0.3 mol catalyst from 50-85 °C temperatures and between 12 and 40 bar pressure. This channel flow is expected to provide increases in mass transfer while high heat transfer capability will accommodate the increased heat transfer duty resulting from increased reaction rates and the absence of the solvent. A simple kinetic model of the data obtained using both reactor types is derived allowing a comparison based on apparent turn-over frequencies. Operation in the HEx reactor was free of mass transfer limitations and the observed turnover frequency was independent of catalyst concentration. By contrast the catalyst productivity in the autoclave was a function of its concentration indicating mass transfer limitations. The observed reaction rate, in terms of apparent turnover frequency was 10-15 times higher in the heat-exchange reactor than the laboratory scale stirred tank. The selectivity to the desired monoaldehyde product was also higher in the HEx reactor. The temperature, pressure and catalyst concentration appear to have little influence of reaction selectivity (for the monoaldehyde) and the product distribution, this being dependent only on the concentration of cyclododecatriene and monoaldehyde. The reasons for this behaviour are discussed in detail. © 2007

Study of carbon monoxide hydrogenation over Au supported on zinc oxide catalysts

Recently, there has been a marked increase in the interest shown in catalysis by gold. It is now recognised that gold has unique properties as a catalyst for many reactions with pre-eminence in the oxidation of carbon monoxide. However, it is also possible that supported gold catalysts can be used for other reactions involving carbon monoxide, for example the water gas shift reaction. Supported gold catalysts have also been shown to be effective for hydrogenation reactions. This paper sets out the possible use of gold as a catalyst for the hydrogenation of carbon monoxide. In particular, we describe the preparation and characterisation of Au/ZnO and Au/ZnO/Al2O 3 as catalysts for the hydrogenation of carbon monoxide to methanol

Experimental evaluation of a three-phase downflow capillary reactor

One reason for the few commercial successes of intensified catalytic multiphase reactors might be that many of these developments inherently incorporate a fixed catalyst, which may not suit an industry that is based on principles of batch manufacture and multiproduct plants. This study evaluates an intensified reactor that encompasses the opportunities demonstrated from structured flows and thin channels, together with a mobile, slurry catalyst, namely, a multicapillary reactor with gas/liquid/suspended catalyst flow. Using the single capillary arrangement, the reaction of resorcinol hydrogenation was shown to be first order in hydrogen and to be operating under kinetic control. The increase of the gas-to-liquid flow ratio showed a positive effect on the observed reaction rate. Comparison of the rate of resorcinol hydrogenation in the capillary reactor with an autoclave under equivalent reaction conditions demonstrated that the rate in the single capillary reactor (SCR) was enhanced by a factor of 7. © 2005 American Chemical Society

Solvent-free oxidation of benzyl alcohol using titania-supported gold-palladium catalysts: Effect of Au-Pd ratio on catalytic performance

The oxidation of benzyl alcohol with molecular oxygen under solvent-free conditions has been investigated using a range of titania-supported Au-Pd alloy catalysts to examine the effect of the Au-Pd ratio on the conversion and selectivity. The catalysts have been compared at high reaction temperature (160 °C) as well as at 100 °C, to determine the effect on selectivity since at lower reaction temperature the range of by-products that are formed are limited. Under these conditions the 2.5 wt. Au-2.5 wt. Pd/TiO2 was found to be the most active catalyst, whereas the Au/TiO2 catalyst demonstrated the highest selectivity to benzaldehyde. Toluene, formed via either a hydrogen transfer process or an oxygen transfer process, was observed as a major by-product under these forcing conditions. © 2007 Elsevier B.V. All rights reserved