Smoking article with mercaptopropyl functionalized sorbent and method

Abstract

Mercaptopropyl functionalized molecular sieves such as mesoporous SBA-15 silica molecular sieves can be prepared via incipient-wetness impregnation of (3-mercaptopropyl)triethoxysilane of up to a loading of about 15 mole %. The functionalized materials are more hydrophobic than parent material, and can be used as adsorbents to reduce the concentration of heavy metal (mercury and/or cadmium-containing) constituents in mainstream smoke. For example, SBA-15 silica comprising a 1% molar loading of mercaptopropyl groups has an adsorption capacity for mercury that is approximately seven to eight times that of un-functionalized parent SBA-15 silica.

1 . A smoking article comprising a sorbent having mercaptopropyl groups bound to an inorganic molecular sieve substrate, wherein the sorbent is capable of reducing the concentration of at least one heavy metal constituent in mainstream smoke.  
   
   
       2 . The smoking article of  claim 1 , wherein the smoking article is selected from the group consisting of a cigarette, a pipe, a cigar and a non-traditional cigarette.  
   
   
       3 . The smoking article of  claim 1 , wherein the sorbent is located in a filter selected from the group consisting of a mono filter, a dual filter, a triple filter, a cavity filter, a recessed filter, and a free-flow filter.  
   
   
       4 . The smoking article of  claim 1 , wherein the heavy metal constituent comprises mercury and/or cadmium.  
   
   
       5 . The smoking article of  claim 1 , wherein the inorganic molecular sieve substrate (a) comprises mesoporous or microporous molecular sieves; (b) is selected from the group consisting of a zeolite, silicate, aluminophosphate, mesoporous silicate, mesoporous aluminosilicate, and mixtures thereof; or (c) comprises a zeolite selected from the group consisting of zeolite ZSM-5, zeolite A, zeolite X, zeolite Y, zeolite K-G, zeolite ZK-5, zeolite Beta, zeolite ZK-4, and mixtures thereof.  
   
   
       6 . The smoking article of  claim 1 , wherein the sorbent comprises (a) (3-mercaptopropyl)silane covalently bound to a zeolite; (b) SBA-15 silica having incorporated therein up to about 15 mole percent of (3-mercaptopropyl)trialkoxysilane with respect to silicon in the SBA-15; or (c) (3-mercaptopropyl)silane covalently bound to a mesoporous silicate.  
   
   
       7 . The smoking article of  claim 1 , wherein the mercaptopropyl group is covalently bound to exterior and interior surfaces of the inorganic molecular sieve substrate and wherein the inorganic molecular sieve substrate is a mesoporous molecular sieve.  
   
   
       8 . The smoking article of  claim 1 , wherein the sorbent is in granular form having a particle size from about 20 mesh to about 60 mesh and/or the smoking article comprises from about 10 mg to about 300 mg or from about 100 mg to about 200 mg of the sorbent.  
   
   
       9 . A cigarette filter comprising a sorbent having mercaptopropyl groups bound to an inorganic molecular sieve substrate, wherein the sorbent is capable of reducing the concentration of at least one heavy metal constituent such as mercury and/or cadmium in mainstream smoke.  
   
   
       10 . The cigarette filter of  claim 9 , wherein the inorganic molecular sieve substrate (a) comprises mesoporous or microporous molecular sieves; (b) is selected from the group consisting of a zeolite, silicate, aluminophosphate, mesoporous silicate, mesoporous aluminosilicate, and mixtures thereof, or (c) comprises a zeolite selected from the group consisting of zeolite ZSM-5, zeolite A, zeolite X, zeolite Y, zeolite K-G, zeolite ZK-5, zeolite Beta, zeolite ZK-4, and mixtures thereof.  
   
   
       11 . The cigarette filter of  claim 9 , wherein the sorbent comprises (a) (3-mercaptopropyl)silane covalently bound to a zeolite; (b) SBA-15 silica having incorporated therein up to about 15 mole percent of (3-mercaptopropyl)trialkoxysilane with respect to silicon in the SBA-15; or (c) (3-mercaptopropyl)silane covalently bound to a mesoporous silicate.  
   
   
       12 . The cigarette filter of  claim 9 , wherein the mercaptopropyl group is covalently bound to exterior and interior surfaces of the inorganic molecular sieve substrate and wherein the molecular sieve is a mesoporous molecular sieve.  
   
   
       13 . The cigarette filter of  claim 9 , wherein the sorbent is in granular form having a particle size from about 20 mesh to about 60 mesh and/or the cigarette filter comprises from about 10 mg to about 300 mg or from about 100 mg to about 200 mg of the sorbent.  
   
   
       14 . The cigarette filter of  claim 9 , wherein the filter is selected from the group consisting of a mono filter, a dual filter, a triple filter, a cavity filter, a recessed filter, and a free-flow filter.  
   
   
       15 . The cigarette filter of  claim 9 , wherein the filter comprises cellulose acetate tow, cellulose paper, mono cellulose, mono acetate, and combinations thereof.  
   
   
       16 . The cigarette filter of  claim 9 , wherein the sorbent is incorporated into one or more cigarette filter parts selected from the group consisting of shaped paper insert, a plug, a space, cigarette filter paper, and a free-flow sleeve.  
   
   
       17 . The cigarette filter of  claim 9 , wherein the sorbent is incorporated with cellulose acetate fibers forming a plug or a free-flow filter element.  
   
   
       18 . The cigarette filter of  claim 9 , wherein the sorbent is incorporated with polypropylene fibers forming a plug or free-flow filter element.  
   
   
       19 . The cigarette filter of  claim 9 , wherein the sorbent is incorporated in at least one of a mouthpiece filter plug, a first tubular filter element adjacent to the mouthpiece filter plug, and a second tubular filter element adjacent to the first tubular element.  
   
   
       20 . The cigarette filter of  claim 9 , wherein the sorbent is incorporated in at least one part of a three-piece filter including a mouthpiece filter plug, a first filter plug adjacent to the mouthpiece filter plug, and a second filter plug adjacent to the first filter plug.  
   
   
       21 . A method of making a cigarette filter, the method comprising incorporating a sorbent into a cigarette filter, wherein the sorbent comprises mercaptopropyl groups bound to inorganic molecular sieve substrate, and wherein the filter is a mono filter, a dual filter, a triple filter, a cavity filter, a recessed filter, or a free-flow filter.  
   
   
       22 . A method of making a cigarette, the method comprising: 
 (i) providing a cut filler to a cigarette making machine to form a tobacco column;    (ii) placing a paper wrapper around the tobacco column to form a tobacco rod; and    (iii) attaching the cigarette filter of  claim 9  to the tobacco rod using tipping paper to form the cigarette.    
   
   
       23 . A method of treating mainstream smoke comprising contacting mainstream tobacco smoke with a sorbent having at least one mercaptopropyl group bound to an inorganic molecular sieve substrate while drawing the smoke through a smoking article, wherein the sorbent reduces the concentration of at least one heavy metal constituent such as mercury and/or cadmium in mainstream smoke.