摘要:
Nitrogen oxides, NO.sub.x, are depleted/removed from oxygen-containing gas streams comprising same, by contacting an admixture of ammonia and such gas streams, at elevated temperatures, with a catalyst which comprises a catalytically active metallic oxide deposited on a porous alumina support, said support comprising a volume of pores having diameters larger than 1000 A in excess of 25 cm.sup.3 /100 g, a volume of pores having diameters larger than 300 A in excess of 40 cm.sup.3 /100 g, a total pore volume of from about 80 cm.sup.3 /100 g to 120 cm.sup.3 /100 g, and a surface area of less than 160 m.sup.2 /g, said catalytically active metallic oxide being an oxide of a metal selected from the group consisting of vanadium, iron and cobalt, and said catalytically active metal oxide comprising from 0.5 to 20% by weight of the catalyst.
摘要:
An active oxidation catalyst having the formula:A.sub.a Mo.sub.c W.sub.d B.sub.b O.sub.xwherein A is at least one of the metals cobalt, nickel, manganese and/or lead; B is at least one of the metals iron, bismuth, chromium and/or thallium; a is the sum of each of the metals A and ranges from greater than zero to about 12; c and d each ranges from zero to 12, with their sum being about 12; b is the sum of each of the metals B and ranges from greater than zero to about 1.5[(c+d)-a]; an x fulfills all unsatisfied valences, is prepared by (I) intimately admixing (i) a first aqueous solution comprising the ammonium salts of the molybdenum and/or tungsten, said ammonium salts being present therein in amounts such as to satisfy the formula parameters c and d, with (ii) a second aqueous solution comprising the salts of the A and/or B metals, at least one of said A and/or B salts being either a nitrate or a chloride and said salts being present therein in amounts such as to satisfy the formula parameters a and b, until a first solids fraction precipitates therefrom; (II) thereafter basicifying the resulting suspension with ammonia to a pH value in excess of the pH of said first aqueous solution, until a second solids fraction precipitates therefrom; (III) recovering said first and said second solids fractions, and drying the same; and (IV) thence calcining said dried solids fractions.
摘要:
Mixed oxide active catalysts having the formula:A.sub.a Mo.sub.c W.sub.d B.sub.b O.sub.xwherein:A is at least one of the metals cobalt, nickel, manganese and/or lead;B is at least one of the metals iron, bismuth, chromium and/or thallium;a is the sum of the values indicating the amounts present of each of the metals A, and is a number ranging from greater than 0 to about 12;c and d are numbers each equal to or greater than 0 and ranging to 12, with the sum c+d being about 12;b is the sum of the values indicating the amounts present of each of the metals B, and is a number ranging from greater than 0 to about 1.5 [(c+d)-a]; andx is a number satisfying all unbalanced valences, are prepared by, in a first stage, intimately admixing in aqueous phase the salts of all metals to comprise such active catalyst, with the salts of molybdenum and/or tungsten being ammonium salts and at least one salt of at least one of the metals A and B being a nitrate or a chloride whereby ammonia is added to an aqueous solution comprising the ammonium salts of molybdenum and/or tungsten in an amount sufficient to adjust the pH thereof to a value ranging from about 6 to 8 and then adding to the resulting solution simultaneously, a second aqueous solution comprising the A and B metal salts and sufficient ammonia to maintain the pH in the range of from about 6 to 8. The resulting suspension is then filtered with the recovered paste being dried and calcined.
摘要:
Mixed oxide active catalysts having the formula:A.sub.a Mo.sub.c W.sub.d Co.sub.e B.sub.b O.sub.xwherein:A is at least one of the metals nickel, manganese and/or lead;B is at least one of the metals iron, bismuth, chromium and/or thallium;a is the sum of the values indicating the amounts present of each of the metals A, and is a number ranging from greater than or equal to 0 to about 4;c and d are numbers each equal to or greater than 0 and ranging to 12, with the sum c+d being about 12;e is a number ranging from about 8 to about 12;b is the sum of the values indicating the amounts present of each of the metals B, and is a number ranging from greater than 0 to about 1.5 [(c+d)-(a+e)]; andx is a number satisfying all unbalanced valences,are prepared by, in a first stage, intimately admixing in aqueous phase the salts of all metals to comprise such active catalyst, with the salts of molybdenum and/or tungsten being ammonium salts and at least one salt of at least one of the metals A and B being a nitrate; and, in a second stage, drying and calcining. In the process, the problems of ammonium nitrate formation are avoided by, in the first stage, acidifying an aqueous solution comprising the ammonium salts of molybdenum and/or tungsten to a pH ranging from about 0.5 to 3, separating the molybdic and/or tungstic acid precipitates which thereby form and preparing an aqueous suspension thereof, and then admixing therewith aqueous solutions of the metal salts of the remaining metals comprising the catalyst.
摘要:
A novel catalyst composition is disclosed which comprises a catalytically-active metal oxide component containing the oxides of cobalt, molybdenum, bismuth, and iron corresponding to the empirical formula:Co.sub.a Mo.sub.12 Fe.sub.b Bi.sub.c O.sub.xwherein:A is a value of between about 8 and about 10,B is a value of between about 0.5 and about 2,C is a value of between about 0.5 and about 2,And x equals the sum of 1.5c+1.5b+a+36 and including a crystalline phase having the empirical formula Bi.sub.2 Mo.sub.2 Fe.sub.2 O.sub.12.The catalyst composition is prepared by subjecting a conventionally prepared precursor composition to a two-step calcination, comprising two calcining procedures at a temperature of 450.degree.-500.degree. C. and an intermediate cooling to ambient temperature. The novel catalysts exhibit a high activity and selectivity in a process for preparing .alpha.,.beta.-unsaturated aldehydes by oxidizing olefins.