Process for manufacturing iron molybdate catalysts of high strength and the use of the resulting catalysts in the catalytic oxidation of alcohols to aldehydes

Claim 2

IN A PROCESS FOR MANUFACTURING A CATALYST CONTAINING CATALYTIC QUANTITES OF IRON AND MOLYBDENUM FROM A CATALYST PRECURSOR, SAID IRON AND MOLYBDENUM BEING THE PREDOMINANT CATALYTIC METALLIC ELEMENTS IN SAID CATALYST AND IN SAID PRECURSOR, THE IMPROVEMENT COMPRISING: A. EMPLOYING AS THE SAID CATALYST PRECURSOR, A HOMOGENEOUS SUBSTANCE CONTAINING MOLYBDATE AND FERRIC IONS IN AN ATOMIC RATIO MO FE OF 1.5-5, WATER IN AN AMOUNT LOWER THAN 10% BY WEIGHT AND IONS OF AN AMMONIUM SALT IN AN AMOUNTS EXPRESSED AS THE WEIGHT OF SAID AMMONIUM SALT, OF 10-50% OF THE DRY WEIGHT OF SAID HOMOGENEOUS SUBSTANCE, AND B. HEATING SAID HOMOGENEOUS SUBSTANCES AT 150-250*C FOR A TIME SUFFICIENT TO ELIMINATE SUBSTANTIALLY ALL THE WATER AND A PORTION OF THE AMMONIUM SALT CONTAINED THEREIN, THEREAFTER MIXING THE PRODUCT RESULTING FROM SAID HEATING WITH WATER OR A CHEMICALLY INERT SOLVENT CAPABLE OF DISSOLVING NOT MORE THAN SAID AMMONIUM SALT, SHAPING SAID MIXTURE, AND HEATING RESULTANT SHAPED MIXTURE TO 150-250*C TO DRY SAME AND TO RESULT IN AN UNACTIVATED CATALYST OF IMPROVED MECHAICAL STRENGTH, SAID UNSACTIVATED CATALYST BEING THEREAFTER CALCINABLE BY HEATING AT 300-500*C TO RESULT IN AN ACTIVATED CATALYST OF IMPROVED MECHANICAL STRENGTH.

Claim 3

A process as claimed in claim 1, wherein said homogeneous substance contains, as the ions of an ammonium salt, ammonium and nitrate ions.

Claim 4

A process as claimed in claim 1, wherein the heating step (b) is continued until the dry weight of loss of said homogeneous substance is 10-30% of its dry weight.

Claim 5

A process as claimed in claim 1, further comprising a step of grinding the product resulting from the heating step (b).

Claim 6

A process as claimed in claim 1, further comprising the step of calcining the unactivated catalyst at 300-500*C to form an activated catalyst.

Claim 7

An unactivated catalyst of improved mechanical strength as produced by the process of claim 1.

Claim 8

An activated catalyst of improved mechanical strength obtained by a process as claimed in claim 5.

Claim 9

A process as claimed in claim 1, wherein said homogeneous substance is a washed precipitate containing molybdate and ferric ions in an atomic ratio Mo/Fe of 1.5 to 4, to which an ammonium salt is added, by malaxating, in an amount corresponding to 0.3-2 moles per gm. equivalent of iron in said precipitate and the water content of which is reduced to less than 10% by weight.

Claim 10

A process as claimed in claim 8, wherein said ammonium salt is ammonium nitrate.

Claim 11

A process as claimed in claim 8, further comprising the step of calcining the unactivated catalyst at 300-500*C to form an activated catalyst.

Claim 12

In a process for manufacturing a catalyst containing catalytic quantities of iron and molybdenum from a catalyst precursor, said iron and molybdenum being the predominant catalytic metallic elements in said catalyst and in said precursor, the improvement comprising: a. employing, as the said catalyst precursor, a homogeneous, amorphous and transparent gel containing molybdate and ferric ions in an atomic ratio Mo/Fe of 1.5-5, water in an amount lower than 10% by weight, and ions of an ammonium salt in an amount expressed as the weight of said ammonium salt, of 30-50% of the dry weight of said homogeneous, amorphous and transparent gel; and b. heating said homogeneous, amorphous and transparent gel at 150-250*C for a time sufficient to eliminate substantially all the water and a portion of the ammonium salt contained therein, thereafter mixing the product resulting from said heating with water or a chemically inert solvent capable of dissolving not more than said ammonium salt, shaping said mixture, and heating resultant shaped mixture to 150-250*C to dry same and to result in an unactivated catalyst of improved mechanical strength, said unactivated catalyst being thereafter calcinable by heating at 300-500*C to result in an activated catalyst of improved mechanical strength.

Claim 13

In a process for manufacturing a catalyst containing catalytic quantities of iron and molybdenum from a catalyst precursor, said iron and molybdenum being the predominant catalytic metallic elements in said catalyst and in said precursor, the improvement comprising: a. employing, as the said catalyst precursor, a homogeneous, amorphous and transparent gel containing molybdate and ferric ions in an atomic ratio Mo/Fe of 1.5-5, water in an amount lower than 10% by weight, and ions of an ammonium salt in an amount expressed as the weight of said ammonium salt, of 30-50% of the dry weight of said homogeneous, amorphous and transparent gel; and b. heating said homogeneous, amorphous and transparent gel at 150-250*C for a time sufficient to eliminate substantially all the water and a portion of the ammonium salt contained therein, thereafter mixing the product resulting from said heating with water or a chemically inert solvent capable of dissolving not more than said ammonium salt, shaping said mixture, and heating resultant shaped mixture to 150-250*C to dry same and to result in an unactivated catalyst of improved mechanical strength, said unactivated catalyst being thereafter calcinable by heating at 300-500*C to result in an activated catalyst of improved mechanical strength.

Claim 14

A process as claimed in claim 11, wherein the heating step (b) is continued until the loss of dry weight of said homogeneous, amorphous and transparent gel is 10-30% of its dry weight.

Claim 15

A process as claimed in claim 11, wherein in said homogeneous, amorphous and transparent gel, up to 50% of the ferric ions is substituted with the ionic equivalent amount of cations of at least one metal selected from the group consisting of cobalt, nickel, manganese, chromium, scandium, yttrium, and the rare earth metals, and up to 50% of the molybdate ions is substituted with the ionic equivalent amount of oxygen-containing anions of at least one metal selected from the group consisting of chromium, tungsten, manganese, vanadium and uranium.

Claim 16

A process as claimed in claim 11, wherein said homogeneous, amorphous and transparent gel contains, as the ions of an ammonium salt, ammonium and nitrate ions.

Claim 17

A process as claimed in claim 11, further comprisinG a step of grinding the product resulting from the heating step (b).

Claim 18

A process as claimed in claim 11, said homogeneous, amorphous and transparent gel having been prepared by a process comprising reacting under stirring at a temperature lower than 20*C an aqueous solution of ammonium molybdate having a concentration of 1-2.5 gram-atoms of molybdenum per liter with an aqueous solution of ferric nitrate having a concentration higher than 1 gram-atom of iron per liter, the relative amounts of the solutions being such that, in their mixture, the atomic ratio Mo: Fe has the value from 1.5 to 5.

Claim 19

A process as claimed in claim 11, said homogeneous, amorphous and transparent gel having been prepared by a process comprising reacting by crushing at a temperature of at most 150*C solid ammonium molybdate and solid ferric nitrate, in the presence of an amount of water lower than the total of the amounts necessary to form individual saturated solutions of said ammonium molybdate and said ferric nitrate, the relative amounts of the solid reactants being such that, in their mixture, the atomic ratio Mo/Fe has the value from 1.5 to 5.

Claim 20

An unactivated catalyst of improved mechanical strength produced according to the process of claim 11.

Claim 21

A process as defined by claim 11, further comprising the step of calcining said unactivated catalyst at 300-500*C to form an activated catalyst.

Claim 22

An activated catalyst of improved mechanical strength produced according to the process of claim 19.