This mini-review provides a critical analysis of recent patents published in the fields of catalysis, more specifically in the context of improving process efficiency. The selectivity, yield and activity of homogeneous and heterogeneous catalysts in relation to both batch and flow processes are discussed. Major breakthroughs in the development of heterogeneous catalysts are covered with a particular emphasis on the use of microencapsulating technologies in C-C bond- forming and hydrogenation reactions. Special attention is given to the use of supercritical CO2 as a green solvent. Finally, as many catalytic reactions and processes will benefit from the highly ‘tuneable’ and functional nature of macromolecular structures, recent progress in synthetic polymer chemistry is discussed, especially in relation to emerging nanoscale polymeric catalysts, and highly porous frameworks with surface areas greater than 5000 m2 g-1.
This review patent summarized the catalytic studies of molybdenum based catalysts for higher alcohols synthesis reported in literature and recent patents. Molybdenum sulfide was the most widely studied catalyst, with Ni, Co, Mn, or Rh as co-catalyst, for higher alcohols synthesis. Molybdenum oxide, molybdenum carbide, and molybdenum phosphide were also reviewed in this paper. Alkali metals, such as K, Rb and Cs, were usually used as promoters. The selectivity of the alkali metal doped MoS2 is strongly dependent on the alkali metal used. Molybdenum based catalysts have the following benefits: 1) the sulfide-based catalysts require 50 to 100 ppm H2S in syngas stream to maintain the sulfidity of the catalyst. Thus, they are sulfur resistant, and sulfur clean up costs might be reduced; 2) the catalysts are less sensitive to CO2 in the syngas stream than other catalysts. However, catalyst activity can still be inhibited with high amounts of CO2 (>30%); 3) carbon coking does not become a problem even with low H2/CO ratio (i.e. < 2); 4) the major product is nonbranched linear alcohols. Oxide-based catalysts tend to be more active than these sulfide-based catalysts. Molybdenum phosphide catalyst gave lower selectivity for higher alcohols.
The major patents concerning chirally modified nickel catalysts by enantiomerically pure tartaric acid are comprehensively surveyed. The methods of catalyst's preparation for attaining a high enantioselectivity and the synthetic routes for obtaining optically active compounds by using these tartaric acid-modified nickel catalysts are summarized. A recently claimed patent dealing with the robust chiral nickel catalyst, which exhibits an exceptionally high stability after preparation is also introduced.
Thermoset resin systems comprising phenols, epoxies and polyfurfuryl alcohol have been used for more than 20 years in the aerospace, automotive, marine and construction sectors where fire and high temperature resistant components are required. The resins, mentioned above, are cured by acid, neutral or alkaline catalysts. Since the reactions are exothermic in nature, the curing process sometimes leads to explosions. It is important, therefore, to review the patents related to the catalysts used in the curing of these resins. Recently, a US patent was filed by the author where it has shown the ways to reduce the chances of explosions frequently observed during the acid catalyzed condensation reactions of polyfurfuryl alcohol. Other patents granted in 2011, show the use of latent curing agents (US8039522 and US7906213) and phenol as a curing agent for epoxy resins (US8008410). A method for producing a thermosetting epoxy resin having a benzoxazine ring is mentioned in US7994270. Carboxylic acids, sulfonic acids and phosphonic acids having at least two acid groups as an acid curing agent for thermoset resins are discussed in US8003750.
Hydromorphone and hydrocodone are widely used narcotic analgesics. In this mini-review article, processes for the preparation of these semi-synthetic opioids from the naturally occurring opiates morphine and codeine, respectively, via catalytic isomerization of the allylic alcohol unit of the latter are discussed. Relevant patents in the field are presented.
Patented Catalysts for the Synthesis and Biological Applications of Dihydropyrimidinones: Recent Advances of the Biginelli Reaction
Pp: 51 - 73
Ricardo A. W. Neves Filho, Martin C. N. Brauer, Mieder A. T. Palm-Forster, Ronaldo N. de Oliveirac and Ludger A. Wessjohann [View Abstract]
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The acid-catalyzed and thermal multicomponent cyclocondensation between an aldehyde, a beta-keto ester and urea to generate dihydropyrimidinones (DHPMs) is one of the best studied multicomponent reactions in organic synthesis. It is frequently employed in the synthesis of natural products and biologically active compounds. After several years under academic development, this reaction drew the attention of researchers in the chemical and pharmaceutical industry. This critical review is focused on the development and applications of the Biginelli three component reaction (B-3CR) patented in the last three decades.
A Novel Catalyst Ag/MgO-CeO2-Al2O3 for the Low-temperature Ethanol- SCR of NO under lean de-NOx Conditions
Pp: 74 - 84
Lilian Y. Valanidou, Christodoulos P. Theologides, Georgios O. Olympiou, Petros G. Savva and Costas N. Costa [View Abstract]
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The present work reports data on a novel catalyst having excellent activity, selectivity and stability for the selective reduction of nitric oxide to nitrogen in the presence of ethanol or ethanol/hydrogen mixture as reducing agent, in the low temperature range of 150-300°C and in the presence of excess oxygen, H2O and SO2 in the feed. The novelty of the present catalyst compared to other patented ones, for the reaction at hand, lies upon the simplicity and the remarkably low Ag loading (wt%) used, characteristics that are required for a practical application. In addition, the latter catalyst shows significant activity (rate of NO reduction) at much lower temperatures (below 300°C) compared to other already patented catalysts. The present inventive catalyst consists of silver crystals that are in contact with a mixed oxide support comprised of MgO, CeO2 and Al2O3 in 1:1:2 wt% ratio. This novel catalyst presents high activity in terms of NO conversion (XNO = 60-90%) and high selectivities towards N2 (SN2 = 92-95%) and CO2 (SCO2 > 97%) in the range of 150-400°C, at a GHSV of 40,000 h-1 and using a feed stream of 0.05vol% NO, 0.1vol% EtOH, 5vol% O2 and 5vol% H2O. To our knowledge, this is the highest selectivity towards N2 and CO2 ever reported. In addition, the current catalyst shows remarkable stability with time on stream and in the presence of 5 vol% H2O and 50 ppm SO2 in the feed stream. After 48 h on stream the patented catalyst retains its stability expressed in high activity (XNO > 80%) and selectivities to N2 (SN2 > 95%) and CO2 (SCO2 > 97%).
In this paper, the recent advances in the preparation of biogenic material by catalysis pathway and the patents obtained by different researchers are discussed in detail. The patents obtained by utilizing the weed biomass are scarce. The catalysis of crude plant cellulose using 2, 2, 6, 6-tetramethyl-piperidine-1-oxy radical (TEMPO) in the presence of sodium bromide and sodium hypochlorite at alkaline pH 10 producing nanofibers is relatively a new method used in the conversion of biomass into biogenic material. The aquatic weed plant cellulose available in a great deal, is otherwise a un utilized biomass. The water insoluble fractions of TEMPO oxidized cattail cellulose fibers (TEMPO-OCCF) are converted into the solubilized fractions of TEMPO oxidized cattail cellulose nanofibrils (TEMPO-OCCNF) by ultrasonication and filtration. The scanning electron micrographs (SEM) indicated that the morphology nanofibrils have 20 nm diameter and the lengths in few micrometers. Differential scanning calorimetry (DSC) results show that the TEMPO treated fibers have enriched with higher thermal stability comparable to untreated cattail fibers. A neat and transparent thin film was prepared by casting the suspension of TEMPO-OCCNF into a Petri dish. The transmittance of the film was confirmed by UVVisible spectrophotometer.