2017 Spring Symposium

Mark Deimund, Exxon­Mo­bil Research and Engi­neer­ing Com­pa­ny, Annan­dale, NJ

Abstract — Two zin­cosil­i­cate mol­e­c­u­lar sieves (CIT-6 and Zn-MCM-41) were syn­the­sized and ion-exchanged with nick­el, allow­ing them to act as cat­a­lysts for the oligomer­iza­tion of propy­lene into C_3n prod­ucts (pri­mar­i­ly C₆ and C₉ species). For per­for­mance com­par­i­son to alu­mi­nosil­i­cate mate­ri­als, two zeo­lites (high-alu­minum beta and zeo­lite Y) were also nick­el exchanged and uti­lized in the oligomer­iza­tion reac­tion.

CIT-6 and the high-alu­minum zeo­lite beta (HiAl-BEA) both have the *BEA frame­work topol­o­gy, allow­ing for com­par­i­son between the zinc and alu­minum het­eroatoms when exchanged with nick­el, as the for­mer gives two frame­work charges per atom, while the lat­ter gives only one. Ni-CIT-6 and Ni-Zn-MCM-41 enable the com­par­i­son of a micro­p­orous and a meso­porous zin­cosil­i­cate. The Ni2+ ion exchanged onto zeo­lite Y has been pre­vi­ous­ly report­ed to oligomer­ize propy­lene and is used here for com­par­i­son.

Reac­tion data are obtained at 180°C and 250°C, atmos­pher­ic pres­sure, and a WHSV = 1.0 h^-1 in a feed stream con­sist­ing of 85mol% propy­lene, with the bal­ance inert. At these con­di­tions, all cat­a­lysts are active for propy­lene oligomer­iza­tion, with steady-state con­ver­sions rang­ing from 3–16%. With the excep­tion of Ni-HiAl-BEA, all cat­a­lysts exhib­it high­er propy­lene con­ver­sions at 250°C than 180°C. Both *BEA topol­o­gy mate­ri­als exhib­it sim­i­lar propy­lene con­ver­sions at each tem­per­a­ture, but Ni-HiAl-BEA is not as selec­tive to C_3n prod­ucts as Ni-CIT-6. Zin­cosil­i­cates demon­strate high­er aver­age selec­tiv­i­ties to C_3n prod­ucts than the alu­mi­nosil­i­cates at both reac­tion tem­per­a­tures test­ed. Hex­ene prod­ucts oth­er than those expect­ed by sim­ple oligomer­iza­tion are also present, like­ly formed by dou­ble-bond iso­mer­iza­tion cat­alyzed at acid sites.

Addi­tion­al­ly, both of the alu­mi­nosil­i­cate mate­ri­als cat­alyzed crack­ing reac­tions, form­ing non-C_3n prod­ucts. The reduced acid­i­ty of the zin­cosil­i­cates rel­a­tive to the alu­mi­nosil­i­cates like­ly accounts for the high­er C_3n prod­uct selec­tiv­i­ty of the zin­cosil­i­cates. Zin­cosil­i­cates also exhib­it­ed high­er lin­ear-to-branched hex­ene iso­mer ratios when com­pared to the alu­mi­nosil­i­cates. The meso­porous zin­cosil­i­cate exhibits the best reac­tion behav­ior (includ­ing C_3n prod­uct selec­tiv­i­ty: approx­i­mate­ly 99% at both tem­per­a­tures for Ni-Zn-MCM-41) of the cat­alyt­ic mate­ri­als test­ed here.

From Deimund, MA, et al. ACS Catal., 2014, 4 (11), pp 4189–4195. DOI: 10.1021/cs501313z

Biog­ra­phy — Orig­i­nal­ly from Okla­homa City, Okla­homa, Mark attend­ed Texas A&M Uni­ver­si­ty where he earned his under­grad­u­ate degree in chem­i­cal engi­neer­ing. He then attend­ed the Uni­ver­si­ty of Cam­bridge for his MPhil, con­duct­ing research into the for­ma­tion of pro­tein deposits in brain cells as a means to bet­ter under­stand the onset of Alzheimer’s and oth­er neu­rode­gen­er­a­tive dis­eases. Upon com­ple­tion of this degree, he began his PhD work at the Cal­i­for­nia Insti­tute of Tech­nol­o­gy in the area of mol­e­c­u­lar sieve syn­the­sis and reac­tion test­ing under Pro­fes­sor Mark E. Davis. Cur­rent­ly, he works as a researcher at Exxon­Mo­bil Research and Engi­neer­ing Com­pa­ny in Annan­dale, NJ.