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Topic: Homogenous catalyst

	Catalyst
		A catalyst in chemistry or biology is a substance that accelerates the rate of a chemical reaction but is unconsumed (net) by the reaction (see also catalysis).
		Heterogeneous catalysts are present in different phases from the reactants in the reaction they are catalysing, whereas homogenous catalysts are in the same phase.
		Homogenous catalysts generally react with one or more reactants to form a chemical intermediate that subsequently reacts to form the final reaction product, in the process regenerating the catalyst.
	www.ebroadcast.com.au /lookup/encyclopedia/ca/Catalyst.html (370 words)

	U.S. Patent: 5536858 - Tetrasulfonated diphosphine compounds and metal complexes thereof for asymmetric catalytic ... (Site not responding. Last check: 2007-10-31)
		It is known that separation of the catalyst from the reaction products and recovery of the catalyst are, next to the activity and selectivity of the catalyst, of major importance to industrial applications of homogeneous catalytic processes.
		Catalyst recovery and catalyst recycling are generally difficult to achieve in an economically and ecologically-sound way, but are of paramount importance in catalytic reactions which require relatively large amounts of catalyst.
		The ruthenium (Ru) catalyst and rhodium (Rh) catalyst derived from the ligand of formula I appears to be of equal enantioselectivity and of similar activity as the corresponding catalyst derived from the non-sulfonated ligand in these hydrogenations.
	www.everypatent.com /comp/pat5536858.html (5906 words)

	CEP MAR '05
		As a catalyst user, it is in your best interest to understand how sampling processes help refiners determine the precious metals content of spent catalysts and, ultimately, the amount (and value) of these metals that is returned to you.
		The catalysts must first be processed to remove those contaminants and achieve free-flowing properties that will ensure accurate sampling, provide a reproducible settlement weight, and also permit safe and efficient operation of the process that will ultimately recover the remaining precious metals.
		The main portion of the catalyst lot, which typically consists of extrudates of the order of 1 cm in length, is then divided by an automatic sampler into one or two bulk samples of a size suitable to achieve the desired precision.
	www.sabinmetal.com /pages/articles_cep-3-05.html (3998 words)

	Catalyst (Site not responding. Last check: 2007-10-31)
		Thus, catalysts are essential to living systems - they are necessary in order to get required reactions to occur on a timescale that is useful for living systems.
		Heterogeneous catalysts are often composed of metals or metal oxides
		If the catalyst makes it easier to break a specific bond, then to maintain the overall reaction enthalpy, the formation of the appropriate new bonds must not result in the release of as much energy (as in the absence of the catalyst).
	wine1.sb.fsu.edu /chm1046/notes/Kinetics/Catalyst/Catalyst.htm (1182 words)

	DNT Selective Catalytic Reduction
		The catalyst is at the heart of the SCR process.
		Catalyst configurations can be homogenous honeycomb, coated honeycomb or plate type catalyst.
		The catalyst opening, composition and volume of catalyst are determined by components of flue gas chemistry, treatment temperature and amount of flue gas to be treated.
	www.de-nox.com /SCR.htm (446 words)

	Catalysis. How a homogenous catalyst works.
		In this section we look at how a homogeneous catalyst works and at some examples of homogeneous catalysis.
		In homogeneous catalysis the reactants, products and catalyst are all in the same phase.
		In these situations the catalyst may be a transition metal ion catalysing a redox reaction.
	www.schoolscience.co.uk /content/5/chemistry/catalysis/catsch7pg1.html (213 words)

	CASOUMM FINAL REPORT MAY 1998, EPSRC GRANT GR\K01124 (Site not responding. Last check: 2007-10-31)
		The first was the modification of an active oxidation centre which was part of a microporous catalyst framework, the second was the modification of a cation associated with a microporous crystalline framework.
		For a variety of alkenes the data obtained were consistent with those observed for the homogeneous reaction and good yields of aziridine could be obtained without use of the large excesses of alkene necessary in the homogeneous process.
		Investigations on the reusability of the catalyst showed that conversion and enantioselectivity were reduced during successive experiments, but that the initial activity of the catalyst could be restored.
	www.cf.ac.uk /chemy/staff/hutch/K01124.html (1225 words)

	Catalyst creates new opportunities
		For the past 2 years, Degussa's cataCXium A catalyst has been used in CX coupling reactions, but its application in reductive carbonylation was stumbled upon recently when the company began screening for a more effective catalyst for this process.
		This homogenous catalyst/ligand process allows a single-step reaction, which does not require large amounts of hazardous chemicals or extreme reaction conditions, compared with other known methods.
		“Catalysts for reductive carbonylation reactions are already available, however, it is now possible to run these reactions more efficiently, with CataCXium A,” Antje Gerber, General Manager, Degussa Homogenous Catalysts, told In-PharmaTechnologist.com.
	www.labtechnologist.com /news/ng.asp?id=64127 (380 words)

	Clay for cleaner production of solvent
		This structure gives rise to a highly active catalyst, which in terms of catalyst particle size and mechanical strength is ideally suited for industrial applications.
		The catalysts currently used for the production of methyl isobutyl ketone from acetone and hydrogen are used in the liquid phase.
		All of the spent catalyst remains in the reaction mixture and must once again be removed via special steps.
	www.eurekalert.org /pub_releases/2006-02/nofs-cfc021506.php (280 words)

	Controlling Reaction Rates
		This particular catalyst is in a different physical state from the reactant - said to be a heterogenous catalyst.
		acts as a catalyst - it is in the same physical state as the reactants - said to be a homogenous catalyst.
		Solid catalysts provide a surface on which the reactant molecules temporarily stick, in the correcy orientation for an easy reaction.
	www.geocities.com /CapeCanaveral/Launchpad/5226/rates.html (1472 words)

	Flask-based photosynthesis
		The closest researchers have come previously to achieving this goal is to use solid photocatalysts but these require massive surface areas to be effective.
		McCusker points out that the MIT success is tempered by certain problems such as the need to close the catalytic loop and remove the halogen without it simply accumulating in a waste product trap.
		The conversion efficiency of this particular catalyst, which also degrades too quickly to be practical in the long-term, are not important at this stage.
	www.reactivereports.com /20/20_1.html (440 words)

	How Small Can You Go?
		Such nanoparticle-based catalysts are heterogeneous catalysts, says El-Shall, but work much like homogeneous catalysts," sometimes even better," because the particles are so small.
		"A homogenous catalyst is very well dispersed because it's contained in the reaction medium," he explains.
		Researchers now are evaluating the nanoparticles for use as catalysts to remove carbon monoxide from air, as well as for use as a "smart dust" that detects chemical and biological warfare agents and environmental pollutants.
	www.chemicalprocessing.com /articles/2003/264.html (2027 words)

	Process for the preparation of n-methyl-3-(1-methyl-4-piperidinyl)-1H-indole-5-ethanesulphonamide - Patent 5786473 (Site not responding. Last check: 2007-10-31)
		Alternatively a homogenous catalyst such as tris(triphenylphosphine) rhodium chloride may be used.
		The reaction will generally be effected in the presence of a palladium catalyst such as, for example palladium or palladium oxide on charcoal or a palladium salt or complex.
		Palladium salts which may be employed as catalysts include salts of organic acids such as acetates or salts of inorganic acids such as chlorides or bromides.
	www.freepatentsonline.com /5786473.html (4208 words)

	Chapter 19
		Catalysts are effective materials because they decrease the activation energy needed for chemical reactions to occur.
		A homogenous catalyst is present in the same phase as the reactants
		The Arrhenius equation states that the rate constant, k, of a reaction is directly proportional to the frequency factor (A), inversely proportional to the activation energy E
	www.iugaza.edu /users/Abdellatif/CHEMB1301/Lectures_1_20/L12.htm (1173 words)

	New method for converting nitrogen to ammonia
		The Chirik team, however, was able to break the nitrogen molecule's atomic bond, using zirconium in a soluble form, at just 45 degrees Celsius (113 degrees Fahrenheit) and add hydrogen atoms to this so-called "dinitrogen bridge." Complete fixation to ammonia was achieved at 85 degrees Celsius (185 degrees Fahrenheit).
		Instead the zirconium makes only one ammonia molecule at a time, not vast numbers as in an industrial process, and, as Fryzuk notes, "there is no known homogenous catalyst that can effect this simple process" at low temperatures and pressure.
		Chirik says his group is currently searching for such a catalyst, which would be patentable.
	www.eurekalert.org /pub_releases/2004-02/cuns-nmf021804.php (586 words)

	Nitrogen-fixing discoverey
		Fryzuk noted that it has taken so long to achieve the Chirik group's transformation of nitrogen because, he said, molecular nitrogen "is so chemically inert that even binding it to metal complexes in solution...
		Instead the zirconium makes only one ammonia molecule at a time, not many as in an industrial process, and, as Fryzuk noted, "there is no known homogenous catalyst that can effect this simple process" at low temperatures and pressure.
		Chirik said his group is currently searching for such a catalyst, which would be patentable.
	www.news.cornell.edu /Chronicle/04/3.4.04/nitrogen.html (580 words)

	Green Plus Fuel Catalyst and Enhancer (Site not responding. Last check: 2007-10-31)
		Green Plus, which is a true liquid catalyst that mixes completely with various types of fuel, is the world's most effective and economical solution for significantly improving fuel economy and reducing emissions.
		Many attempts to add different types of catalysts to fuel have been tried, but they are generally heavy metal-based materials that are extremely expensive and tend to simply drop out and fall to the fuel tank floor.
		Green Plus is a homogenous catalyst that is completely miscible with almost all kinds of fuel, effectively creating a mini
	www.biofriendly.com /greenplus.htm (386 words)

	Catalyst (Site not responding. Last check: 2007-10-31)
		OMG is a longtime leader in the production of hydrocarbonsoluble and water-reducible metal organics for use as homogenous catalysts or precursors for heterogeneous chemical processing catalysts.
		Transition metals, like nickel are important organic chemical industry catalysts.
		Cobalt, in several different forms, is used as an important transition catalyst for a variety of industries.
	www.omgi.com /industries/catalyst.htm (62 words)

	"This Divided State's" Cinematic Scintillation \| Catalyst Magazine (Site not responding. Last check: 2007-10-31)
		Premiered in February on the UVSC campus, this challenging film attracted interest from major Hollywood studios and independent distributors, and now has a chance of getting picked up for national or regional release.
		What Greenstreet and his colleagues have captured is a riveting closeup of contrasting ideologies in divided college and off-campus communities -- this in what conventional wisdom deems the most conservatively homogenous county in the country's reddest state.
		But as a document of political awakening at a surprisingly feisty state college, the film has universal appeal.
	www.catalystmagazine.net /issues/story.cfm?story=514 (878 words)

	Chemical Communications Articles
		The direct addition of NH across a CC multiple bond (hydroamination) was efficiently catalysed in a liquid—liquid two-phase system.
		The latter comprised a polar catalyst phase of Zn(CF in the ionic liquid 1-ethyl-3-methylimidazolium trifluoromethanesulfonate and a substrate mixture in heptane.
		The possibility of catalysing different hydroamination reactions continuously was demonstrated.
	rsc.org /Publishing/Journals/CC/article.asp?DOI=b111630d&... (71 words)

	UNL College of Engineering - Department of Chemical and Biomolecular Engineering (Site not responding. Last check: 2007-10-31)
		These processes normally involve an inorganic homogenous catalyst and high temperatures and pressures.
		The immobilized catalyst by entrapment exhibits thermal stabilization and increased activity over the free enzyme form.
		In order to engineer a stable, economical, and highly active immobilized enzyme for commercial application, one has to provide feedback to the catalyst improvement studies regarding pore size distributions, specific surface areas, and enzyme distribution within the immobilized gel.
	www.unl.edu /cheme/faculty/Noureddini.shtml (573 words)

	Shaughnessy research
		By understanding these fundamental reaction steps, we attempt to develop new or improved synthetic methods relying on organometallic catalysts.
		We are interested in efforts to use "environmentally benign" solvents in metal-catalyzed reactions both to lessen the amount of waste produced and to allow recovery and recycling of the homogenous metal catalyst.
		Using water-soluble catalysts in the modification of hydrophilic biomolecules, such as nucleosides.
	bama.ua.edu /~kshaughn/research/research.html (574 words)

	crabtree NHCs (Site not responding. Last check: 2007-10-31)
		Our work is directed at the design and synthesis of NHCs, and catalysts derived from them, to aim for desired catalytic properties.
		In other studies, we developed NHC catalysts for Heck, Sonogashira, and Suzuki couplings, as well as transfer hydrogenation, hydrosilylation and dehydrogenation reactions.
		Peris E, Loch JA, Mata J, Crabtree RH: A Pd complex of a tridentate pincer CNC bis-carbene ligand as a robust homogenous Heck catalyst.
	www.chem.yale.edu /~crabtree/nhc.htm (336 words)

	Homogenizers on ThomasNet.com (Site not responding. Last check: 2007-10-31)
		This Industrial directory contains a broad range of Homogenizers related companies which can be researched using this premier vertical portal.
		Our comprehensive range of Homogenizers related companies have been complied in this industrial portal designed to provide information on manufacturers, distributors and service companies.
		Company Profile: Manufacturer of mechanical deaerators/defoamers/degassers capable of removing entrapped air & foam from liquids while simultaneously mixing, blending, homogenizing, emulsifying & dispersing the...
	www.thomasnet.com /products/homogenizers-38640801-1.html (804 words)

	Zinc Oxide Nanowires Make Nifty Nanolasers
		, "A Pd complex of a tridentate pincer CNC bis-carbene ligand as a robust homogenous Heck catalyst," Chem.
		The secret of their production is first to imprint on the sapphire surface a thin layer of a gold template.
		It is from this that the crystals grow, the gold acting as a catalyst to promote the creation of the nanowires.
	www.sciencewatch.com /nov-dec2002/sw_nov-dec2002_page7.htm (857 words)

	General Catalyst Partners :: News
		Many payers find it difficult or cost-prohibitive to connect with multiple clearinghouses, and may settle for low quality and poor customer service from a single EDI provider.
		With access to the eClaims Gateway™ that merges the GTESS Mailroom services with our Partner Clearinghouses, payers gain a clean, homogenous stream of EDI claims, customized to auto-adjudicate, and all the accrued benefits of a single operational portal for quick, efficient customer service.
		In fact, GTESS’ fully integrated products are built upon a connective architecture that provides a single, streamlined workflow for all claims processing operations, creating new levels of cost savings and efficiency and opening the door for future applications.
	www.generalcatalyst.com /news/articles/gtess_051017.html (489 words)

	Crystal Engineering of Functional Polymeric Metal-Organic Frameworks
		The solid catalysts can be readily recovered by simple filtration and reused five times without loss of activity and enantioselectivity.
		Bu, a wide range of aromatic ketones have been hydrogenated with e.e.’s in the range of 91.0-99.2% and turnover frequency as high as 700 h
		The solid catalysts have been recovered and reused for 8 times without the loss of activity and enantioselectivity.
	www.unc.edu /~wlin/Research3.htm (875 words)

	biochemistry coursework
		As I was varying concentration I expected a curve that would level off at some point.
		However, I found that the curve resembled that of a homogenous catalyst, with an increasing yield to a maxium point then a decrease.
		I can only think that the strong acid was reacting in someway with the sugars.
	www.physicsforums.com /showthread.php?t=108555 (430 words)

	Biofriendly Green Plus Texas (Site not responding. Last check: 2007-10-31)
		Green Plus, which is a true liquid catalyst that disperses entirely throughout the fuel, can be added in extremely low concentrations (50 ppm or less).
		Green Plus is a homogenous catalyst that is completely miscible with almost all kinds of fuel, effectively creating a mini-catalytic converter in the engine or combustion system.
		Biofriendly Corporation are the makers of Green Plus Combustion catalyst.
	green-plus-texas.com (126 words)

	crabtree publications (Site not responding. Last check: 2007-10-31)
		Peris E, Crabtree RH: Recent homogeneous catalytic applications of chelate and pincer N-heterocyclic carbenes.
		Peris E, Crabtree RH: New routes to carbene complexes for thermally and oxidatively robust homogeneous catalysts.
		Crabtree RH: Alkane C-H activation and functionalization with homogeneous transition metal catalysts: a century of progress-a new millennium in prospect.
	www.chem.yale.edu /~crabtree/publications.htm (1289 words)

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