Particulate Matter (PM) is one of the major harmful substances in diesel exhaust gas. Technologies like the Diesel Particulate Filter (DPF) and Diesel Oxidation Catalyst (DOC) have been positioned at the exhaust to reduce the quantity of harmful substances released to the environment. This paper highlights the factors that affect combustion in diesel engines and the potential of the introductio...

Frequently the activity of fresh catalyst changes with time in use. The decrease or increases of the catalyst activity with time during the course of reaction forces the system to an unsteady state operation ([1], [2], [3], [4] and [5]). One of these catalysts is the copper/zinc oxide catalyst, which is industrially used for methanol production. The activity of copper/zinc oxide catalyst declin...

Deprotection of various phenols from their respective methoxymethyl ethers using an heteropolyacid catalyst was studied. The catalyst was the Wells-Dawson heteropolyacid, used both in bulk or supported on silica. Yields were high to quantitative after less than one hour reaction time and the catalyst was easily recoverable and reusable.

The lifetime (200 h) of a Cu/SiO(2) catalyst under DMO-ethanol feedstock is 20 times longer than that (10 h) of the catalyst under DMO-methanol feedstock without any modification of the catalyst. The stabilization effect of ethanol on the active centers can effectively slow down the agglomeration of copper particles during the hydrogenation process.

Attempts are made to define the “ideal synthesis”, “ideal catalyst”, and “ideal recoverable catalyst”. Although these unattainable limits can never be realized, they help to focus attention on attributes chemists should strive for. Criteria for evaluating catalyst recovery are analyzed, and increased attention to the critical and constructive evaluation of competing “green” chemical technologie...

The vital role of ethylenediaminetetraacetic acid on the structure and the oxygen reduction reaction activity of the non-precious-metal-based pyrolyzed catalyst is reported and elaborated. The resultant catalyst can overtake the performance of commercial Pt/C catalyst in an alkaline medium.

A new microporous metal-organic framework compound featuring chiral (salen)Mn struts is highly effective as an asymmetric catalyst for olefin epoxidation, yielding enantiomeric excesses that rival those of the free molecular analogue. Framework confinement of the manganese salen entity enhances catalyst stability, imparts substrate size selectivity, and permits catalyst separation and reuse.

The approach using pyrrolidine enamine as substrate has been studied for this synthesis, and an important catalyst structural feature has been developed. After survey of pyrrolidine-based Brønsted acid catalyst, tetrazole catalyst (3f) was found to be optimal in synthesis of aminooxy carbonyl compounds in high yields, with complete enantioselectivity not only for aldehydes but also for ketones.

The regiodivergent palladium-catalyzed C-H arylation of pyrazolo[1,5-a]pyrimidine has been achieved, wherein the switch in regioselectivity between positions C3 and C7 is under complete catalyst control. A phosphine-containing palladium catalyst promotes the direct arylation at the most acidic position (C7), whereas a phosphine-free catalyst targets the most electron-rich position (C3).

The upper rim cone tetraguanidinocalix[4]arene 1 is a highly effective catalyst of ATP hydrolysis. The catalytically most active species is the triprotonated form of the catalyst. The three protonated guanidinium groups provide the electrostatic driving force for substrate binding and activation, while the neutral guanidine most likely acts as a nucleophilic catalyst.