Desktop Molecular Modeling Help in Clarifying Odd Experimental Observations on Zeolites and Silica Gels

2012 Spring Symposium

Ist­van Halasz
PQ Cor­po­ra­tion

Abstract — Zeo­lites and amor­phous sil­i­ca gels are wide­ly used in adsorp­tion and catal­y­sis. PQ com­mer­cial­izes sil­i­ca based mate­ri­als by tai­lor­ing them to spe­cif­ic cus­tomer needs world­wide. These mod­i­fi­ca­tions usu­al­ly require series of mate­r­i­al tests which most­ly car­ried out at the company’s R&D Cen­ter where I have been assigned to inves­ti­gate the poros­i­ty, acid­i­ty, sorp­tion capac­i­ty, activ­i­ty and oth­er tar­get­ed prop­er­ties of exper­i­men­tal and com­mer­cial prod­ucts. Some­times these exper­i­ments lead to unex­pect­ed, sur­pris­ing, con­tra­dic­to­ry results which usu­al­ly gen­er­ate var­i­ous spec­u­la­tive expla­na­tions. In this pre­sen­ta­tion I’ll illus­trate through a few exam­ples how mol­e­c­u­lar mod­el­ing can help in resolv­ing con­flicts between ideas and empir­i­cal find­ings. I intend to show that the com­mon­ly avail­able com­put­er pow­er and mod­el­ing pro­grams have devel­oped so much dur­ing the past few years that even an exper­i­men­tal­ist with lim­it­ed resources and the­o­ret­i­cal back­ground can mim­ic var­i­ous empir­i­cal data which is the basis to under­stand­ing mate­r­i­al prop­er­ties at the mol­e­c­u­lar lev­el. It will be also shown how com­put­er chem­istry can lead to improved quan­tifi­ca­tion of oth­er­wise rou­tine­ly mea­sured mol­e­c­u­lar spec­tro­scop­ic data. The pre­sent­ed exam­ples will include mod­el cal­cu­la­tions based on force field relat­ed Monte Car­lo algo­rithm, time depen­dent den­si­ty func­tion­al the­o­ry, and a com­bi­na­tion of quan­tum mechanical/molecular mechan­i­cal meth­ods. Sim­u­lat­ed exper­i­men­tal sorp­tion isotherms and FTUV spec­tra of two hydropho­bic zeo­lites will be pre­sent­ed to explain their unusu­al sorp­tion prop­er­ties and redox cat­alyt­ic activ­i­ties. More­over, we com­pare the mod­el and exper­i­men­tal FTIR and laser Raman spec­tra of some amor­phous sil­i­cates and present the first exper­i­men­tal proof that sil­i­ca gels obtained from aque­ous alka­line sil­i­cate solu­tions or tetra-eth­yl-orthosil­i­cate at acidic or basic con­di­tions can have dis­tinct mol­e­c­u­lar struc­tures which affect their final phys­i­cal prop­er­ties.

Speaker’s Biog­ra­phy — Ist­van obtained a physics and chem­istry teacher diplo­ma from the Lajos Kos­suth Uni­ver­si­ty, Hun­gary. Lat­er he was award­ed magna cum laude doc­tor­ate degree from the same uni­ver­si­ty and a high­er degree from the Hun­gar­i­an Acad­e­my of Sci­ences, HAS. Fol­low­ing three years of teach­ing phys­i­cal chem­istry, he joined the Hun­gar­i­an Hydro­car­bon Insti­tute, where he devel­oped new, eco­nom­ic process­es for phar­ma­ceu­ti­cal, fine chem­i­cal and petro­chem­i­cal plants and stud­ied the fun­da­men­tals of acid-base catal­y­sis over met­al oxides. As a young sci­en­tist he won sev­er­al com­pet­i­tive awards and a research schol­ar­ship for the Uni­ver­si­ty of Tech­nol­o­gy in Vien­na, Aus­tria. After 12 years of indus­tri­al research, he moved to the Chem­i­cal Research Insti­tute of HAS where his major research top­ics includ­ed shape selec­tive catal­y­sis on zeo­lites and syn­the­sis of high tem­per­a­ture ceram­ic super­con­duc­tors. Ist­van also worked as post­doc­tor­al researcher at Wayne State Uni­ver­si­ty and Uni­ver­si­ty of Iowa, focus­ing main­ly on the cat­alyt­ic abate­ment of auto­mo­bile exhausts and indus­tri­al stack gas­es. He joined PQ near­ly 14 years ago. He has been mem­ber of sev­er­al sci­en­tif­ic orga­ni­za­tions and cur­rent­ly serves as pres­i­dent of NECZA (North East Cor­ri­dor Zeo­lite Asso­ci­a­tion). Ist­van has authored and co-authored more than 180 pub­li­ca­tions.