Activated carbons with molecular sieve membranes and their use as adsorbents in smoking articles

Abstract

A composite for use in smoking articles such as cigarettes is described comprising a zeolite membrane coated upon an activated carbon-containing substrate. The substrate may be a fiber, fabric, particle, granule or monolith. The composite is prepared by contacting zeolite precursors with the substrate and hydrothermally synthesizing the membrane upon the substrate. The substrate may be pretreated to provide activation sites for adhesion and growth of the membrane. By selection of the zeolite components, the composite may be tailored to selectively remove constituents of tobacco smoke while simultaneously controlling access to the substrate thereby prolonging the shelf life of the activated carbons.

1 . A smoking article comprising tobacco and a filter component comprising a composite comprising at least one activated carbon-containing substrate coated with at least one zeolite molecular sieve layer.  
   
   
       2 . The smoking article of  claim 1 , wherein said substrate comprises a fiber, fabric, particle, granule or monolith, and the zeolite comprises a crystalline alumino-silicate, a silicoaluminophosphate or a micro- or meso-porous molecular sieve.  
   
   
       3 . The smoking article of  claim 2 , wherein the zeolite comprises a molecular sieve selected from ZSM-5, X, Y or A type zeolites.  
   
   
       4 . The smoking article of  claim 1 , wherein the article is a cigarette.  
   
   
       5 . The smoking article of  claim 1 , wherein the substrate is pretreated to provide nucleation sites.  
   
   
       6 . The smoking article of  claim 5 , wherein the pretreatment comprises reaction with a silane.  
   
   
       7 . The smoking article of  claim 1 , wherein the activated carbon of the substrate has a distribution of micropores, mesopores and macropores.  
   
   
       8 . The smoking article of  claim 4 , wherein the filter component is a mono filter, a dual filter, a triple filter, a cavity filter, a recessed filter or a free-flow filter, the filter component comprises cellulose acetate tow, cellulose paper, polypropylene fiber or combinations thereof, and the composite is incorporated into at least one cigarette filter part selected from a shaped paper inset, a plug, a space, cigarette filter paper or a free-flow sleeve.  
   
   
       9 . A smoking article comprising a filter component composed of a composite comprising at least one activated porous carbon substrate and at least one zeolite molecular sieve membrane coated on the surface of and/or in the pores of the substrate.  
   
   
       10 . The smoking article of  claim 9 , wherein said carbon substrate is pretreated to provide nucleation sites.  
   
   
       11 . The smoking article of  claim 10 , wherein pretreatment comprises reaction with a silane.  
   
   
       12 . The smoking article of  claim 9  comprising tobacco cut filler, cigarette paper and cigarette filter material, wherein the a composite is capable of selectively removing constituents from cigarette smoke, and wherein the composite is prepared by hydrothermally synthesizing a zeolite molecular sieve layer on said substrate.  
   
   
       13 . The smoking article of  claim 12 , wherein said article is a cigarette.  
   
   
       14 . A method of treating cigarette smoke produced by the cigarette of  claim 4 , comprising lighting the cigarette to form tobacco smoke and drawing the tobacco smoke through the cigarette, wherein the composite reduces the amount of selected constituents in the tobacco smoke, and wherein the composite is located in a filter component of the cigarette.  
   
   
       15 . The cigarette according to  claim 13  comprising tobacco and a filter element, wherein the filter element includes the composite comprising an activated porous carbon substrate having a zeolite molecular sieve membrane coated upon and within the pores of the substrate, wherein the carbon substrate comprises a fiber, fabric, particle, granule or monolith.  
   
   
       16 . The cigarette of  claim 15 , wherein the carbon substrate has been pretreated with a silane to provide nucleation sites.  
   
   
       17 . A method of manufacturing a cigarette filter, comprising incorporating into a cigarette filter a composite comprising a porous activated carbon-containing substrate and a zeolite molecular sieve membrane coated upon and within the pores thereof, the composite being loaded on a support, or incorporated in a support, or incorporated with a support, in a plug-space-plug arrangement, in bead form, and/or in monolith form.  
   
   
       18 . A method of treating mainstream smoke of a smoking article of  claim 13 , by contacting mainstream smoke with the porous composite, wherein the porous composite selectively removes at least one selected constituent from mainstream smoke.  
   
   
       19 . The method of  claim 18 , wherein said selected constituent removed is at least one of an aldehyde, ketone, hydrocarbon, aromatic, HCN, a nitrile, CO, a polar or non-polar organic compound or mixtures thereof.