Active material compositions with porous protective sheath and method for preparing

Claim 2

A structurally strong particulate composite of active materials comprising a core and a microporous sheath surrounding said core, said core containing the active material selected from group consisting of catalysts, adsorbants, microsieves, ion exchangers or mixtures thereof in particulate form and said microporous sheath consisting of a solid, strengthening, enclosing structure for said core having an open porous structure including communicating open pores forming passageways for access to said core from the space surrounding said sheathed composite, said porous structure resulting from sintering a sheath-forming material admixed with an organic material that is combustible at sintering temperatures, said sheath-forming material being a crystalline or amorphous inorganic salt or oxide selected from the group consisting of fused alumina, silicon carbide, alumina, silica, zirconia, feldspar, sodium glass, lead glass, borosilicate glass, Portland cement and amorphous alumina cements and said communicating open pores resulting from the combustion of said combustible organic material thereby providing voids comprising said passageways for access to said core from the space surrounding said particulate composite.

Claim 3

The particulate composition according to claim 1 wherein said core of active material is separated from said surrounding sheath by an open space whereby volume changes of said active material do not disrupt the continuity of said surrounding sheath.

Claim 4

The composite according to claim 1 wherein said microporous sheath material includes a further active material.

Claim 5

The composite according to claim 1 wherein said active material is thermally activated.

Claim 6

The composite according to claim 1 wherein said particulate cores comprise a plurality of layers, each layer comprising an active material which may be the same or different from said other layers.

Claim 7

The particulate composite according to claim 1 wherein said strengthening structure of said microporous sheath has a crush strength greater than 3 kg Kiya Hardness Test and wherein the thickness of said sheath is in the range of 5 to 100% of the inside diameter of said sheath.

Claim 8

The particulate composite according to claim 1 wherein said microporous sheath has pore sizes in the range 0.05 to 100μ, an apparent porosity in the range 20 - 70% and a pore volume in the range 0.01 to 0.7 cc/gm.

Claim 9

The composition according to claim 1 wherein said active material is manganese dioxide catalyst.

Claim 10

The process for the preparing particulate composites according to claim 1 wherein said active materials are enclosed by a structurally stronger sheath which comprises the steps of a) shaping individual cores comprising said active material in particulate form, b) coating said cores with a coating composition of sheath-forming material comprising (1) a structural component of crystalline and amorphous inorganic oxides, salts and mixtures thereof selected from the group consisting of fused alumina, silicon carbide, alumina, silica, zirconia, feldspar, sodium glass, lead glass, borasilicate glass, Portland cement, amorphous alumina cements; (2) a binder component for binding said structural component; and (3) a fugitive component, said fugitive component being selected from among organic compounds which are combustible at sintering temperatures; c) then forming said coat into a microporous sheath by heating, said coated cores to elevated sintering temperatures thus sintering said coat on said cores, and combusting said fugitive material during said heating step to concurrently form pores in the voids previously occupied by said fugitive component.

Claim 11

The process according to claim 9 wherein said individual cores are formed by the process of granulation, tableting or mechanical subdivision.

Claim 12

The method according to claim 9 for preparing a catalyst for methylating phenols which comprises the steps of granulating manganese oxide to size, with a binder, to form a core, coating said core with a sheath-forming coating material and said sheath-forming material being a crystalline or amorphous inorganic salt or oxide selected from the group consisting of fused alumina, silicon carbide, alumina, silica, zirconia, feldspar, sodium glass, lead glass, borosilicate glass, Portland cement and amorphous alumina cements and sufficient water to form said coating mixture, drying said coating and then heating said coated composite to sintering temperature to form the particulate composite of a core coated with a sintered microporous sheath.

Claim 13

The process according to claim 9 wherein said active material is a manganese dioxide catalyst.

Claim 14

The process for preparing particulate composites wherein said active materials are enclosed by a structurally stronger sheath which comprises the steps of a. shaping individual cores comprising said active material in particulate form, b. coating the cores in the first coat of fugitive material c. further coating said cores with a second coat of a coating composition of sheath-forming material comprising 1. a structural component of crystalline and amorphous inorganic oxides, salts and mixtures thereof selected from the group consisting of fused alumina, silicon carbide, alumina, silica, zirconia, feldspar, sodium glass, lead glass, borosilicate glass, Portland cement, amorphous alumina cements; 2. a binder for said composition component; and 3. a fugitive component, said fugitive component being selected from among material which are combustible at sintering temperatures; d. then forming said second coat into a microporous sheath by heating said coated cores to elevated sintering temperatures thus sintering said second coat around said cores, and also combusting said fugitive material from said first and second coats during said heating step to concurrently form voids in the spaces previously occupied by said fugitive component.

Claim 15

The process for preparing particulate composites wherein said active materials are enclosed by a structurally stronger sheath which comprises the steps of a. shaping individual cores comprising said active material in particulate form, b. coating the cores in the first coat of fugitive material c. further coating said cores with a second coat of a coating composition of sheath-forming material comprising 1. a structural component of crystalline and amorphous inorganic oxides, salts and mixtures thereof selected from the group consisting of fused alumina, silicon carbide, alumina, silica, zirconia, feldspar, sodium glass, lead glass, borosilicate glass, Portland cement, amorphous alumina cements; 2. a binder for said composition component; and 3. a fugitive component, said fugitive component being selected from among material which are combustible at sintering temperatures; d. then forming said second coat into a microporous sheath by heating said coated cores to elevated sintering temperatures thus sintering said second coat around said cores, and also combusting said fugitive material from said first and second coats during said heating step to concurrently form voids in the spaces previously occupied by said fugitive component.