A study to test the concept of new protector plus condom variants.

Thesis (MBA)-University of KwaZulu-Natal, Westville, 2006.No abstract available.Pages i - v, and vii - 5 missing in digitized copy

Hemicellulose hydrolysis catalysed by solid acids

Depolymerising hemicellulose into platform sugar molecules is a key step in developing the concept of an integrated biorefinery. This reaction is traditionally catalysed by either enzymes or homogeneous mineral acids. We compared various solid catalysts for hemicellulose hydrolysis, running reactions in water, under neutral pH and relatively mild temperature and pressure (120 °C and 10 bar) conditions. Sulphonated resins are highly active, but they leach out sulphonic groups. Sulphonated silicas are less active, but more stable. They have weakly and strongly bound sites and the strongly bound ones do not leach. Zeolites are moderately active and stable. Among them, H-ferrierite especially, despite its small pores, exhibited high activity as well as good recyclability

Hydrolysis of oligosaccharides over solid acid catalysts: a review

Mild fractionation/pretreatment processes are becoming the most preferred choices for biomass processing within the biorefinery framework. To further explore their advantages, new developments are needed, especially to increase the extent of the hydrolysis of poly- and oligosaccharides. A possible way forward is the use of solid acid catalysts that may overcome many current drawbacks of other common methods. In this Review, the advantages and limitations of the use of heterogeneous catalysis for the main groups of solid acid catalysts (zeolites, resins, carbon materials, clays, silicas, and other oxides) and their relation to the hydrolysis of model soluble disaccharides and soluble poly- and oligosaccharides are presented and discussed. Special attention is given to the hydrolysis of hemicelluloses and hemicellulose-derived saccharides into monosaccharides, the impact on process performance of potential catalyst poisons originating from biomass and biomass hydrolysates (e.g., proteins, mineral ions, etc.). The data clearly point out the need for studying hemicelluloses in natura rather than in model compound solutions that do not retain the relevant factors influencing process performance. Furthermore, the desirable traits that solid acid catalysts must possess for the efficient hemicellulose hydrolysis are also presented and discussed with regard to the design of new catalysts

Novel Bimetallic Cobalt Catalysts for the Direct Amination of Alcohols

International audienc

Oxidation of d-Glucose to Glucaric Acid Using Au/C Catalysts

The reactivity of Au and AuBi nanoparticles supported on activated carbon AC was investigated in the direct oxidation of glucose to glucaric acid. The catalysts were very active, regardless of the Au nanoparticles size, but the catalyst with the smallest average particle diameter was the least selective to glucaric acid because of the enhanced consecutive oxidative degradation of the intermediately formed gluconic acid. The reaction network included the fast oxidation of glucose to gluconic acid, which was the only primary product, and its consecutive oxidation into either glucaric acid or lighter mono and dicarboxylic acids. The best glucaric acid yield obtained with a AuBi/AC catalyst (Au/Bi 3:1) was 31 %, with 18 % residual gluconic acid. The control of reaction parameters was essential to achieving the best selectivity. Specifically, the glucose concentration turned out to be a critical parameter in relation to O2 pressure and to glucose/metal ratio

Ru and Ag promoted Co/Al2O3 catalysts for the gas-phase amination of aliphatic alcohols with ammonia

International audienceThe present paper describes the synthesis of primary amines from long-chain aliphatic alcohols and ammonia using alumina-supported noble metal doped cobalt formulations with moderate cobalt loading (5 wt%). The influence of the noble metal nature, loading and impregnation sequence was studied in detail and comprehensively characterized using XRD, H2-TPR, CO-TPD and STEM-EELS/EDS. While all noble metals exerted a positive effect on the cobalt reducibility, Ag and Ru impacted to a higher extent the activity and selectivity for amine synthesis. The impregnation protocol was found to be critical with the best results being obtained for sequentially impregnated Ag–Co and co-impregnated Co(Ru) catalysts. Further optimization of the Ag and Ru metal loading led to two formulations affording a comparable activity to that of an alumina-supported catalyst containing 2.4 times more Co. At optimized conditions, the best formulation (5 wt% Co, 3 atom% Ag) afforded 90% conversion and 78% yield to 1-octylamine in the gas-phase amination reaction of 1-octanol with ammonia at 200 °C using 21 equiv. of ammonia compared to 1-octanol, which overcomes the maximum reported yield on benchmark Ni-alumina formulations (70%). Furthermore, this formulation showed high stability for at least 6 h on stream. A survey of the effect of the reaction variables on the catalytic performance revealed a co-catalytic effect of Ag, impacting positively both the activity and selectivity