Biomedical subjects
Publications and source records attributed to Pierre A Jacobs.
n-Alkane hydroisomerisation and hydrocracking experiments reveal that ZSM-5 materials synthesized by self-assembly of nanoslabs show different molecular shape selectivity than ZSM-5 synthesized by hydrothermal methods.
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[reaction: see text] Electrophilic activation of hydrogen peroxide can be achieved in acidic alcohol solvents without the need for a metal catalyst. This concept is illustrated by the epoxidation of alkenes with H(2)O(2) employing phenol as a solvent. It is proposed that intermolecular hydrogen bonding between H(2)O(2) and phenol activates H(2)O(2) for oxygen-atom transfer. In this interaction, the role of phenol is purely catalytic.
Although transition-metal complexes are very attractive as homogeneous catalysts in fine chemistry, their high prices often limit their applications. A means to recycle those catalysts would solve this problem and would simultaneously facilitate the downstream purification of the product. This is now realized in a new concept in which homogeneous catalysis is coupled to dialysis. The advantages of homogeneous catalysis (off-the-shelf catalysts, high activities and selectivities) are thus combined with those of heterogeneous catalysis (easy catalyst separation from product solution, reuse of catalyst, and possibility for continuous operation). Since the heart of the process is the membrane, self-prepared membranes were preferred as they allow a better control and understanding of the separation characteristics. Rhodamine B was used as a probe molecule to define the working conditions of the membrane. The concept is proven to work for two relevant chiral reactions: a hydrogenation with Ru-BINAP and a hydrogen transfer reaction with Ru-TsDPEN [BINAP=(1,1'-binaphthalene)-2,2'-diylbis(diphenylphosphine); TsDPEN= tosyl-N,N'-diphenyl-1,2-ethanediamine].
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Using layered double hydroxides as a support, both the palladium catalyst and the cobalt co-catalyst are heterogenised and proven to form an acceptable catalytic system for the heterogeneous oxidative carbonylation of phenol to diphenyl carbonate (DPC).
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Optimization of the Mo-V-Sb mixed-oxide system for the selective oxidation of isobutane to methacrolein by true combinatorial methods primarily is intended to reduce the number of experiments in a broad parameter space. Therefore, an evolutionary approach based on a genetic algorithm has been chosen to screen three generations of 30 catalysts. With the help of automated sol-gel synthesis techniques, a high-throughput continuous flow reactor (16UPCFR), and appropriate software for experimental design, a new catalyst composition with improved performance has been obtained. Finally, the best catalysts were scaled-up to gram quantities and tested in a continuous-flow reactor unit that was equipped with four parallel reactors (4UPCFR). The final catalyst showed a significantly higher selectivity toward methacrolein at the same isobutane conversion, compared to the initial Mo8V2Sb90O(x) catalyst.
Combinatorial strategies are for the first time applied in membrane technology and prove to be a powerful new tool in the search for novel membrane materials. The selected system for this study is a polyimide solvent-resistant nanofiltration membrane prepared via phase inversion. The phase inversion process is a typical membrane synthesis procedure involving a large number of compositional components, which can each be varied in a wide concentration range. The optimization of the membrane dope composition was performed using evolutionary optimization via genetic algorithms. Compared with the best commercially available membranes, a substantially improved membrane performance could be realized, both on the level of membrane selectivity and on that of permeability. The miniaturized high-throughput synthesis procedure could be scaled up successfully when the polymer dope was sufficiently viscous. It can be anticipated that application of combinatorial techniques can potentially lead to major improvements in all fields of membrane technology, for example water treatment, gas separation, and dialysis, not only on the compositional level but also for instance on the level of membrane synthesis posttreatment and operational conditions.