Recent Patents on Catalysis (Discontinued) - Current Issue

We report on a performance of the photocatalytic solar energy convertors based on mesoporous TiO2 films with immobilized enzymes and membrane pigment-protein complexes of bacterial reaction centers Rhodobacter sphaeroides and Synechocystis sp. PCC 6803 photosystem-I (PS I) using our patented immobilization technique. These semiconductor- enzymes-pigment-protein systems functioned as both the light-harvester and charge separator in photocatalytic and solar cells self-assembled on nanostructured semiconductors. We described our recent patents on different possibilities of electrons photogeneration in the TiO2 conduction band (c.b.) as well as possibilities to use the potential of e- in the TiO2 c.b for the catalytic reduction of H+ to molecular hydrogen and for reduction of NAD+ (NADP+) to NADH(NADPH) by immobilized enzymes. We also report on femtosecond dynamics of charge separation in PS I with relation to these photocatalytic solar energy convertors.

In this review, recent developments in fine chemicals synthesis, catalysis, microreactor design and applications are discussed. Specifically, new advances in continuous micro process engineering, packed-bed devices and photoreactors are discussed to include recent patents in these areas. In addition, new energy sources including ultrasounds and microwaves integrated into microstructured reactors are also discussed. Novel progress in materials to build these devices such as single walled nanotubes are discussed with respect to their properties and synthesis. This approach foresees developments in the use of nanomaterials in microreactor design and the impact these will have in the synthesis and purification of different fine chemicals in continuous flow devices.

This patent survey emphasizes applications of photocatalyst incorporated cement based materials. The patents from two companies, i.e., Italcementi and Toto Ltd., were emphasized in the manuscript due to their greater number of patents. The product survey reflected the current commercial photocatalysis market. Construction sector applications dominated the patents and products.

Isomerization of p-diisopropylbenzene (p-DIPB) to m-diisopropylbenzene (m-DIPB) was carried out using metal modified Hβ zeolites at high temperature and in the absence of a solvent. The metal cations used for the modification of Hβ were typical Lewis acidic cations Fe3+, Al3+, Ti4+, Sn4+ and Sb3+. The modified zeolite catalysts were heated at 120°C, and calcined at 280°C, and 550°C. They were characterized by XRD, FE-SEM, HR-TEM, FT-IR, N2-desorption (BET), NH3-TPD, Pyridine-IR and TGA techniques for structural, morphological, acidity and stability investigation. Particle size of the crystallites was determined by HR-TEM analysis and the size was in the range of 15-35 nm. At 250°C, Al- Hβ, Fe-Hβ and Ti-Hβ showed 68-75% conversion of p-DIPB and 42-54% selectivity towards m-DIPB. The calcination temperature had no effect on the activity. Isomerization increases with increased acidity. Thus, metal modified Hβ catalysts are excellent, efficient, and alternative heterogeneous catalysts for the isomerization of p-diisopropylbenzene (p- DIPB) to m-diisopropylbenzene (m-DIPB). This process is a greener alternative for the classical AlCl3 process as discussed in the article along with the relevant patents.

Photocatalysis is an important process used in the decomposition of chemical residues, which are mostly xenobiotics present in contaminated water. The hydroxyl radical technology using a semiconductor with low energy UV light source has the advantage of oxidation and decomposition process when compared to other conventional techniques resulting in the decomposition of toxic chemicals to non toxic CO2 and water. The early patents on the use of photolysis and photo catalysts go back to 1930 where hydrogen peroxide was used in the presence of direct sun light. Subsequently, introduction of metal catalysts played a role in enhancing the decomposition process of chemicals at industrial level. The thrust for the maximum utilization of solar energy and the introduction of several nano catalysts during the past decade has led to the development of several designs that automate the process of decontamination of pesticide residues at industrial level. Apart from the sunlight, UV and IR, the addition of sonication, heating and flow through systems have added additional advantages to the decomposition technique. The new methods patented have facilitated the decontamination of residues of pesticides which are insecticides, herbicides, fungicides acaricides etc in broad category or the so called xenobiotics from the aquifers, surfaces of fruits and vegetables a boost to the food industry. The cleaning or decomposing process takes place in the aqueous phase with the aid of formation of hydroxyl / oxygen free radicals and in the presence of transition metal catalysts which are mostly metal oxides and semiconductors. The TiO2 catalyst, in different forms, from micro to nano and coated / doped are extensively used in several of these processes due to its easy excitation under direct sunlight / UV light facilitating the transfer of photon energy to the molecule to breakdown into small and non toxic fragments.