Abstract: A method for hydrothermal synthesis of 3D Bi4MoO9/TiO2 nanostructure heterojunction includes the following step: adding Bi(NO3)3.5H2O into distilled water to form a white turbid liquid, and adding an alkaline solution into the white turbid liquid until a potential of hydrogen value of the white turbid liquid is between 3 and 7, thereby obtaining a suspension A; adding TiO2 nanospheres into the suspension A to form a mixed suspension C; adding Na2MoO4.2H2O into distilled water to be dissolved to obtaining a Na2MoO4 solution; adding the Na2MoO4 solution into the mixed suspension C to form a mixture, and adding an alkaline solution into the mixture until a potential of hydrogen value of the mixture is greater than 7, thereby obtaining a mixed suspension D; transferring the mixed suspension D to a closed vessel for a hydrothermal reaction to obtain a hydrothermal synthesis product; and washing and drying the hydrothermal synthesis product.

Abstract: A process is described for the production of formaldehyde, comprising (a) subjecting methanol to oxidation with air in a formaldehyde production unit thereby producing a formaldehyde-containing stream; (b) separating said formaldehyde-containing stream into a formaldehyde product stream and a formaldehyde vent gas stream; wherein the vent gas stream, optionally after treatment in a vent gas treatment unit, is passed to one or more stages of: (i) synthesis gas generation, (ii) carbon dioxide removal, (iii) methanol synthesis or (iv) urea synthesis.

Abstract: The invention relates to a process for preparation of at least one of methacrylic acid and a methacrylic acid ester, comprising the process stepsgas phase oxidation of at least one C4 compound, quenching of the reaction phase, separation and purification of the obtained methacrylic acid and optionally esterification, wherein the C4 compound is a methacrolein comprising mixture, originating from at least two different methacrolein sources, a first methacrolein source being a feed stream obtained by the heterogeneously catalyzed gas phase oxidation of isobutylene or tert-butyl alcohol or isobutylaldehyde or a mixture of two or more thereof, a second methacrolein source being a feed stream obtained by the reaction of propionaldehyde with a C1 extending agent, preferably formaldehyde, and where said methacrolein can be obtained either completely from the first methacrolein source, or completely from the second methacrolein source or from any mixture of both.

Abstract: The use of a supported noble metal catalyst obtainable by applying a sparingly soluble noble metal compound to a support from solution or suspension, and subsequently treating thermally, for preparing olefinically unsaturated carbonyl compounds.

Abstract: The present invention relates to compounds of formula (I): and pharmaceutically acceptable salts thereof, wherein R1 and R2 are as defined herein. The invention also relates to pharmaceutical compositions comprising these compounds, methods of using these compounds in the treatment of various diseases and disorders, processes for preparing these compounds and intermediates useful in these processes.

Abstract: A method of production of a catalyst that has 0.05-0.25 wt. % of precious metal, preferably for the oxidative dehydrogenation of olefinically unsaturated alcohols, comprising the following steps a) producing a D.C. plasma, b) introducing the metal and support material into the plasma, c) evaporating the metal and support material or “shattering” the solid bodies of metal and support material in the plasma, and reaction of the particles, d) cooling, so that very small particles of composite material are obtained, e) applying the composite material on the catalyst support proper, the correspondingly produced catalyst and use thereof.

Abstract: Supported noble metal-comprising catalysts which can be obtained by a) application of colloidal noble metal in the form of a colloidal solution, optionally in admixture with additives acting as promoters, to a support material, b1) drying of the resulting product at from 150 to 350° C., or b2) drying of the resulting product at from 150 to 350° C. and subsequent calcination at from 350 to 550° C. for epoxidation or oxidative dehydrogenation, a process for producing it, its use and also the use of colloidal noble metal for producing supported catalysts.

Abstract: A process for preparing olefinically unsaturated carbonyl compounds by oxidative dehydrogenation in an oxygenous atmosphere over a supported catalyst which comprises gold and optionally further noble metals at temperatures in the range from 50 to 240° C.

Abstract: The present invention discloses a novel use of a catalyst with core-porous shell structure, which includes carrying out an oxidation of an alcohol in vapor phase and in the presence of the catalyst with core-porous shell structure to form an aldehyde or ketone, wherein the catalyst with core-porous shell structure is constituted of a core material and a porous shell material. The core material is a metal having a catalytic activity, and the shell material is a porous inorganic oxide.

Abstract: A method wherein a methanol-containing gas stream is passed in contact with a catalyst comprising a supported or unsupported bulk vanadate catalyst in the presence of an oxidizing agent for a time sufficient to convert at least a portion of the methanol to formaldehyde (CH2O).

Abstract: A catalytic process for the oxidation of organic. Oxygen is loaded into a metal foil by heating the foil while in contact with an oxygen-containing fluid. After cooling the oxygen-activated foil to room temperature, oxygen diffuses through the foil and oxidizes reactants exposed to the other side of the foil.

Abstract: A process and fixed bed reactor for oxidizing methanol in a reactant gas feed stream to formaldehyde. The process comprises introducing the reactant gas feed stream into an upstream region containing a first metal molybdate catalyst (substantially free of a volatile Mo/MoO3 species) under oxidizing conditions to form a partially oxidized reactant gas feed stream which is then introduced under oxidizing conditions into a downstream region containing a second metal molybdate catalyst to further oxidize any residual methanol contained therein. A fixed bed reactor comprising an upstream region and a downstream region containing the aforementioned first and second metal molybdate catalysts, respectively, is utilized to implement the inventive process to yield a product gas stream containing formaldehyde preferably at a conversion of 85% or more and a selectivity of 90% or more.

Abstract: Alkylene glycol is oxidized in a vapor phase in the presence of alcohol (a), oxygen, and a catalyst (a) (primary reaction). &agr;-oxoaldehyde, and alcohol (b) or olefin, are oxidized in a vapor phase in the presence of oxygen and a catalyst (b) (secondary reaction). A molar ratio of the alkylene glycol to the alcohol (a) is preferably in a range of 1/100 to 5/1. It is preferable that one same compound is used as the alcohol (a) and the alcohol (b). In the case where the primary and secondary reactions are successively executed, a reaction device in which a primary reactor and a secondary reactor are connected in a two-stage connection type is preferably used. This ensures that a method is provided that is capable of producing &agr;-oxoaldehyde at a higher yield than conventionally, and further, that is capable of stably obtaining an &agr;-oxoaldehyde solution or gas with a higher concentration than conventionally.

Abstract: A particularly useful process which includes the steps of providing a feedstream comprising a soluble condensation promoting component capable of activating a heterogeneous acidic catalyst and a source of formaldehyde formed by conversion of dimethyl ether in the presence of a catalyst comprising silver as an essential catalyst component; and heating the feedstream with the heterogeneous acidic catalyst in a catalytic distillation column to convert methanol and formaldehyde present to methylal and higher polyoxymethylene dimethyl ethers and to separate the methylal from the higher polyoxymethylene dimethyl ethers is disclosed. Advantageously, methylal and higher polyoxymethylene dimethyl ethers are formed and separated in a catalytic distillation column.

Abstract: Carbonyl compounds of the formula where R1 is a hydrogen atom or an alkyl radical having from 1 to 3 carbon atoms, R2 is a hydrogen atom, an unsubstituted or C1-C3-alkyl-monosubstituted to -trisubstituted C2-C4-alkenyl radical or a radical of the formula where R3 is a hydrogen atom or together with R4 is an oxygen atom, R4 is the radical OR6 or together with R3 is an oxygen atom, R5 is a hydrogen atom, an alkyl radical having from 1 to 8 carbon atoms, an unsubstituted or C1-C3-alkyl-monosubstituted to -trisubstituted C2-C4-alkenyl radical or a cyclohexyl or cyclopentyl radical and R6 is an alkyl radical having from 1 to 4 carbon atoms, a cyclohexyl or cyclopentyl radical or a radical of the formula —CH2—CHO or —CH2—CH2—O—CH2—CHO, are prepared by gas-phase oxidation of methanol or alcohols of the formula where R1 and R5 are as defined above, by means of an oxygen-containing gas in the presence of copper- and/or silv

Abstract: A process for the catalytic conversion of methanol to formaldehyde wherein a gas stream containing methanol and oxygen is contacted with a silver catalyst in a first conversion zone containing a silver catalyst to produce an effluent containing formaldehyde, unreacted methanol, and oxidation byproducts; and contacting the first zone effluent with a copper catalyst in a second conversion zone for further conversion of the unreacted methanol. No molecular oxygen is added to the first stage effluent or to the second conversion zone.

Abstract: In a process for preparing carbonyl compounds of the formula ##STR1## where R.sup.1 is a hydrogen atom or an alkyl radical having from 1 to 3 carbon atoms, R.sup.2 is a hydrogen atom or a radical of the formula ##STR2## where R.sup.3 is a hydrogen atom or together with R.sup.4 is an oxygen atom, R.sup.4 is the radical OR.sup.6 or together with R.sup.3 is an oxygen atom, R.sup.5 is a hydrogen atom, an alkyl radical having from 1 to 8 carbon atoms or a cyclohexyl or cyclopentyl radical and R.sup.6 is an alkyl radical having from 1 to 4 carbon atoms, a cyclohexyl or cyclopentyl radical or a radical of the formula --CH.sub.2 --CHO or --CH.sub.2 --CH.sub.2 --O--CH.sub.2 --CHO, by gas-phase oxidation of methanol or alcohols of the formula ##STR3## where R.sup.1 and R.sup.5 are as defined above and R.sup.7 is a hydrogen atom or a radical OR.sup.8 and R.sup.8 is a hydrogen atom, an alkyl radical having from 1 to 4 carbon atoms, a cyclohexyl or cyclopentyl radical or a radical for the formula --CH.sub.2 --CH.sub.

Abstract: The present invention relates to a process for the preparation of carbonyl compounds of the formula ##STR1## in which R.sup.1 denotes a hydrogen atom or an alkyl radical containing from 1 to 3 carbon atoms, R.sup.2 denotes a hydrogen atom or a radical of the formula ##STR2## in which R.sup.3 denotes a hydrogen atom or, together with R.sup.4, an oxygen atom, R.sup.4 denotes the radical OR.sup.6 or, together with R.sup.3, an oxygen atom, R.sup.5 denotes a hydrogen atom or an alkyl radical containing from 1 to 8 carbon atoms or a cyclohexyl or cyclopentyl radical, and R.sup.6 denotes an alkyl radical containing from 1 to 4 carbon atoms, a cyclohexyl or cyclopentyl radical or a radical of the formula--CH.sub.2 --CHO or --CH.sub.2 --CH.sub.2 --O--CH.sub.2 --CHO,by gas-phase oxidation of methanol or alcohols of the formula ##STR3## in which R.sup.1 and R.sup.5 have the meanings specified above and R.sup.7 denotes a hydrogen atom or a radical OR.sup.8, and R.sup.

Abstract: A process for continuous industrial production of unsaturated aliphatic aldehydes having a boiling range from 95 to 136.degree. C. by oxidative dehydrogenation of the corresponding alcohols with an oxygen-comprising gas over a supported catalyst consisting of copper, silver and/or gold on an inert support in a tube bundle reactor, rapid cooling of the reaction gases and removal of the aldehydes from the resulting condensate with recycling of the unconverted alcohols comprisesa) vaporizing the alcohol,b) admixing the alcohol vapor with an oxygen-comprising gas,c) initially passing the resulting oxygen-comprising alcohol vapor at above the dew point of the alcohol but below the commencement temperature of the reaction through a layer of one of the abovementioned supported catalysts which is at least 0.5 cm in thickness and only thend) reacting the oxygen-comprising alcohol vapor at from 300 to 600.degree. C.

Abstract: A process for preparing formaldehyde by oxidative dehydrogenation of methanol comprises passing a gas mixture (i) comprisinga) from 0.1 to 50% by volume of methanol,b) from 0.1 to 30% by volume of oxygen,c) from 0 to 50% by volume of nitrogen oxide andd) from 0 to 60% by volume of water at from 150 to 800.degree. C. through a phosphorus-doped silver catalyst fixed bed (a) and applying from 0.01 to 100 ppm by weight of phosphorus, based on the phosphorus-doped silver catalyst fixed bed, in the form of a finely divided phosphorus compound having a melting point or decomposition temperature of more than 500.degree. C. (phosphorus compound P) to the phosphorus-doped silver catalyst fixed bed (a) per kg of methanol which is passed through in the form of the gas mixture (i) per cm.sup.2 of the cross-sectional area of the phosphorus-doped silver catalyst fixed bed (a).

Abstract: The process uses a supply column and additional heat exchangers associated with absorption columns. Air and methanol from outside and a subcurrent of methanol, originating from a cold methanol current exiting from the supply column, are fed to the supply column. This exiting current recirculates through the additional heat exchangers and is divided into the subcurrent which returns to the supply column and another subcurrent which is fed to an evaporator. A methanol-air mixture exits from the head of the supply column and is fed to an evaporator. The cold methanol is cooled in the supply column by evaporation of the methanol forming part of the methanol-air mixture.

Abstract: Synthesis of small quantities of compounds such as methanol from reagents, especially radio-labelled reagents such as .sup.11 C oxides, in a carrier gas by a catalytic reaction using a catalyst that has been pre-conditioned for the reaction by previous use for the desired reaction and has then been passivated, or has been maintained in the pre-conditioned state, until contacted with said carrier gas. Where the product is adsorbed by the catalyst, it may be desorbed by heating or displaced by contacting the catalyst with a material, e.g. a catalyst poison that is more strongly adsorbed. Such a more strongly adsorbed material may react with the adsorbed catalytic product to produce a desired product.

Abstract: Catalysts, catalyst precursors, and catalytic systems are provided. The catalysts generally comprise a substrate that includes a group IB metal and a porous, microcrystalline layer that includes the metal and that is disposed on at least a portion of the substrate. The catalysts are prepared by providing a substrate that includes group IB metal, oxidizing said substrate in the presence of stainless steel to produce an oxide coating of said group IB metal, and reducing substantially all of said oxidized substrate.

Abstract: The preparation of 3-alkoxycarbonyl propenals and 3-dialkoxymethyl propenals of the general formulae Ia and Ib respectively: ##STR1## (R.sup.1 =C.sub.1 -C.sub.3 -alkyl group; R.sup.2 and R.sup.3 =hydrogen, methyl, or ethyl; and R.sup.4 and R.sup.5 =C.sub.1 -C.sub.4 -alkyl groups, which may be joined to form a 5-membered or 6-membered ring), is effected by reacting a corresponding alcohol of the general formula IIa or IIb ##STR2## with oxygen or an oxygen-containing gas in the gas phase in the presence of a metal from Group IB of the Periodic Table or a compound of one such metal acting as catalyst.The target products serve as intermediates for the synthesis of carotenoids.

Abstract: In a tube bundle reactor for carrying out catalytic organic reactions in the gas phase, comprising reaction tubes (A) arranged between tubesheets (B), the reaction tubes have an inside diameter ranging from 0.5 to 3 cm, the ratio of reaction tube length to inside diameter ranges from 2 to 10, and the reaction tubes (A) are surrounded by a fluid heat transport medium flowing in the crosswise direction; said tube bundle reactor is useful in particular in exothermic organic reactions.

Abstract: A process for the preparation of carbonyl compounds by the oxydehydrogenation of (C.sub.1 -C.sub.4)-alcohols is carried out at a temperature from 400.degree. to 700.degree. C. in the presence of a silicate catalyst which has been doped with silver and silver ions. By means of the process carried out at relatively low temperatures, for example, are that high yields are achieved, the content of carbon monoxide is low and the product gas contains, apart from carbon dioxide, no further determinable by-products and has a low water/formaldehyde ratio.

Abstract: In the process for making glyoxal by catalytic oxidation of ethylene glycol in contact with catalyst comprising copper, glyoxal yield is improved and catalyst life is improved by the presence of a small amount of iodine or organic iodide in the reactant feed mixture.

Abstract: A process for preparing a dialdehyde which comprises subjecting a glycol to oxidation-dehydrogenation in the presence of silver particles of which the surface is partially coated with a silicon carbide powder or a silicon nitride powder. According to the present invention, dialdehydes can be prepared from glycols in high conversion of the glycol in high selectivity into the dialdehyde, and the silver catalyst can be reused even if the reaction is stopped in a while since the silver particles are not aggregated during long time operation.

Abstract: A process for the preparation of carbonyl compounds by oxidation of alcohols in the gas phase with a gas containing oxygen in the presence of catalysts containing copper and silver.

Abstract: Aldehydes and ketones of the general formula I ##STR1## where R.sup.1 is hydrogen or an organic radical of 1 to n carbon atoms and R.sup.2 is a non-aromatic organic radical of 1 to m carbon atoms, (m+n) ranging from 2 to 24 and R.sup.1 and R.sup.2 being combinable to form a 4- to 12-membered ring, are prepared in a continuous manner by oxidizing an alcohol of the general formula II ##STR2## with oxygen or an oxygen-containing gas at elevated temperatures in the gas phase in the presence of a catalyst, by effecting the oxidation by means of a supported catalyst composed of an inert carrier having a smooth surface and from 0.1 to 20% by weight, based on the amount of carrier, of an active layer of copper, silver and/or gold in a tubular reactor or tube bundle reactor where the internal diameter D of the tube or tubes ranges from 10 to 50 mm and the largest diameter d of the coated supported catalysts is subject to the relationship d=from 0.1 to 0.2 D.

Abstract: A process for the preparation of carbonyl compounds by oxidation of alcohols in the gas phase with a gas containing oxygen in the presence of catalysts containing copper or silver and a phosphorus compound that is volatile under the conditions of the reaction, the ratio of the mass of phosphorus to the mass of the alcohol being less than 0.5 ppm.

Abstract: A supported silver catalyst having improved thermostability is prepared by depositing silver particles on a carrier or support having a stepped structure.

Abstract: An aqueous formaldehyde solution having a formaldehyde concentration of 37 to 60% by weight is produced with less consumption of methanol under methanol-rich mild reaction conditions from a feed gas containing methanol, air, and steam, and, if necessary, an inert gas by subjecting the feed gas to catalytic reaction over a silver catalyst, contacting the resulting product gas with absorbing water, thereby absorbing the formaldehyde into the absorbing water from the product gas in an absorption column, and recovering the desired aqueous formaldehyde solution as bottoms of the absorption column, wherein a total of a corresponding amount of water to that of steam to be added to the feed gas and a necessary amount of water for adjusting the concentration of the product aqueous formaldehyde solution is added to the top of the absorption column as the absorbing water, and an aqueous solution containing 0.1 to 3.0% by weight of methanol and 0.1 to 1.

Abstract: Formaldehyde is prepared by (a) passing a mixture of methanol and water with a concentration of between 50 and 90% by weight, based on the total weight of the two substances, of methanol into a packed column which possesses a packing having a total layer thickness of not less than 50 cm and a total surface area of not less than 0.5 cm.sup.2 per cm.sup.3 of packing, a liquid circulation of from 15 to 90 g/min per g/min of methanol fed to the column, and a concentration of from 10 to 45% by weight of methanol in the recycle liquid, the temperature at the point of entry of the recycle liquid in the column being from 50.degree. to 86.degree. C. and the bottom temperature being 10.degree.-25.degree. C. lower than this, i.e. from 40.degree. to 70.degree. C., (b) separating off methanol and water from the column by stripping with air, an inert gas and/or exit gas, the throughput being from 0.5 to 3 tonnes of methanol and water per hour per m.sup.

Abstract: Glyoxal may be produced with a high yield by bringing a gas, which has been formed by diluting ethylene glycol and molecular oxygen with an inert gas, into contact at a high temperature with a silver catalyst in the simultaneous presence of phosphorus or a phosphorus compound so as to effect the gas phase oxidation of the ethylene glycol.In the above process, it is possible to suppress the formation of glycolaldehyde, a reaction intermediate, and also to enhance the stability of the reaction by using silver powder having particle sizes of 1.times.10.sup.-3 mm or smaller as at least part of the silver catalyst.

Abstract: Glyoxal is prepared by oxidizing glycol in the presence of a silver catalyst, with subsequent or partial condensation of glycol, glyoxal, glycol aldehyde, formaldehyde and/or water by treatment with water or aqueous glyoxal solution in fine dispersion, under specific conditions with regard to the temperature and dispersion of the treatment liquid.The glyoxal which can be prepared by the process of the invention is a wrinkle-resist agent, an assistant for increasing the tear strength and elasticity of fiber materials, a tanning agent, a photographic hardener and a valuable starting material for the production of synthetic resins, textile assistants, paper assistants and plastics.

Abstract: Methanol is converted to formaldehyde by oxidative dehydrogenation using as catalyst sputtered or ion plated silver or silver/gold alloy on an inert hard, nonporous support.

Abstract: An oxidation catalyst comprising boron phosphate impregnated with from 5 to 20 weight percent silver and its use to oxidize propylene, butene-1, butadiene-1,3 and methanol is disclosed. The oxidation takes place at from 200.degree. to 700.degree. C. Preferably water vapor is present.

Abstract: Formaldehyde manufacture by oxidative-dehydrogenation of methanol over a silver or copper catalyst. Aqueous formaldehyde solution is obtained from the reaction and is stripped of a mixture of methanol, formaldehyde and water by a low energy process at relatively low temperature and low reflux in a still comprising at least about 1.5 theoretical plates, the stripping conditions being selected to allow substantial reduction of the methanol content of the aqueous formaldehyde solution and recycle of the methanol to the reactor.

Abstract: The invention relates to a process for purifying, by treatment with an acid ion exchanger and, if desired, a basic ion exchanger, the methanol employed in the preparation of formaldehyde.

Abstract: In a process for oxidizing methanol to formaldehyde which comprises passing the methanol with molecular oxygen through two sequential silver-based catalysts, with the second of said catalysts being a bed of particulate silver such as, specifically, silver crystals, the process efficiency, and especially the efficiency of the reaction taking place in the second catalyst bed, is improved by controlling (a) the ratio of formaldehyde to methanol in the reactant gases entering the second catalyst bed and (b) the specific reaction rate in said second bed. The specific reaction rate is defined as the quantity of methanol converted in said second bed per unit time per unit of cross-sectional area of the bed.

Abstract: A process for the continuous preparation of 3-alkyl-buten-1-als by oxidative dehydrogenation of 3-alkyl-buten-1-ols at from 320.degree. to 650.degree. C. with oxygen over a catalyst containing copper and/or silver, wherein, within one second after contact with the catalyst, the vaporous reaction mixture, which is at from 320.degree. to 650.degree. C., is brought into contact with a liquid comprising water and/or the condensed reaction mixture at from -20.degree. to 50.degree. C., and the 3-alkyl-buten-1-als are separated off from the resulting condensate.

Abstract: A process for converting methanol to formaldehyde at 450.degree. to 750.degree. C. using as catalyst silver, silver-gold alloys or copper-gold alloys in which from 0.001 to 15 parts per million, based on methanol, of phosphorus or phosphorus from a phosphorus compound is present.

Abstract: A process for the oxidative dehydrogenation of methanol to form formaldehyde using silver crystals as catalyst which silver crystals are supported on a screen formed of an alloy containing at least 20 weight percent gold and the remainder silver is disclosed.

Abstract: New catalysts comprising lead and silver on supports having relatively low surface areas and their use have been found to be useful in the oxidative dehydrogenation of methanol to formaldehyde at elevated temperatures.

Abstract: This invention is concerned with catalysis. More especially, the invention relates to catalytic metal or alloy or both in a form having enhanced catalytic properties, and to the use thereof in catalytic processes. In more detail a catalyst or catalyst substrate according to the invention comprises at least one metal and/or alloy body made by a melt spun or a melt extraction process.

Abstract: Lead-silver catalysts have been found to be useful in the production of formaldehyde by oxidative dehydrogenation of methanol vapor with an oxygen-containing gas at elevated temperatures.

Abstract: Aqueous formaldehyde solutions containing minor amounts of methanol are substantially stripped of methanol by a low energy process at relatively low temperature by means of recycled inert gas in a stripping column comprising at least about 1.5 theoretical transfer units for stripping methanol.

Abstract: Formaldehyde manufacture by oxidative-dehydrogenation of methanol over a silver or copper catalyst. Aqueous formaldehyde solution is obtained from the reaction and is substantially stripped of methanol by a low energy process at relatively low temperature by means of recycled off-gas in a stripping column comprising at least about 1.5 theoretical transfer units for stripping methanol.

Abstract: A process for preparing a granular, supported silver catalyst by: contacting refractory porous granules having a tap volume of about 1 to 2 grams per cubic centimeter with water or a water soluble liquid having a boiling point of less than about 150.degree. C. so as to wet said granules and to absorb water or said soluble liquid within peripheral pores of said granules; contacting the wet granules with an ammoniated solution containing a silver salt which decomposes on calcination at a temperature below about 600.degree. C. and a fatty acid having from about 12 to 22 carbon atoms, the quantity of silver salt in said solution being sufficient to provide a metallic silver deposit onto said granules of from about 1 to 10% by weight of said dry granules; drying the silver solution on the granules, and heating the dried granules at a temperature sufficient to decompose the dried silver compounds to metallic silver.