Hydrogen-Rich Gas Production by Upgrading of Biomass Pyrolysis Vapors over NiBEA Catalyst: Impact of Dealumination and Preparation Method

Abstract

The main goal of this work was to develop a highly active catalyst in lignocellulosic biomass conversion to hydrogenrich gas. The studies were focused on the evaluation of an impact of dealumination of BEA zeolites on the catalytic performance of nickel-containing BEA zeolite catalysts in the investigated process. In order to increase an efficiency of hydrogen production, the effect of the catalyst preparation method was investigated (XRD, TEM, TPR, TPD-NH 3 , TG-DTA-MS and BET). During catalytic activity tests, cellulose and pinewood were initially pyrolyzed at 500 °C. The formed vapors were subsequently upgraded by passing them through a catalyst bed at 700 °C. The composition of the mixture of gaseous products was analyzed using GC-MS. The obtained results showed that Ni on dealuminated SiBEA zeolite, characterized by high number of vacant T atom sites, large surface area, high contribution of micropores, and relatively small pore size, was the most active among studied catalysts. The performed research demonstrated that increased reducibility of an active phase was beneficial for the enhancement of hydrogen production. The role of acid−base and redox sites as well as the influence of the state of Ni centers on the activity of Ni-containing dealuminated and nondealuminated BEA systems was also discussed. It is worth noticing that synthesized NiBEA zeolite catalysts, contrary to reference NiZSM-5 (possessing lower surface area and pore volume, lower reducibility and larger Ni crystallites), did not lose their activity in the conversion of lignocellulosic biomass in comparison to decomposition of pure cellulose.

Biodiesel Upgrading to Renewable Diesel over Nickel Supported on Natural Mordenite Catalysts

“…Various methods have been adopted for the preparation of nickel–zeolite catalysts. Among them the relatively simple physical mixing, the incipient wetness impregnation (IWI), the wet impregnation (WI), the encapsulation, the deposition–precipitation (DP), and the ion exchange method have been studied. − Some of them (e.g., ion-exchange) are limited to relatively low metal loading while other results to relatively low dispersion of metal (e.g., IWI). However, studies appearing in the literature concerning the influence of the preparation method of nickel–zeolite catalysts on their efficiency for transforming fatty compounds to fuels are scarce …”

Effect of dealumination and desilication of beta zeolite on performance of nickel catalysts in hydroisomerization for bio-jet fuel production

“…This was possible that the interaction between Ni particles and surface of dealuminated zeolite was stronger resulting in the higher degree of Ni dispersion from 1.67% to 4.43-5.22%. [59,61]. For the use of the higher HF concentration (0.50-0.75 M), the higher reduction temperature which was 660 °C on Ni/beta-0.25M-deA catalyst shifted to lower temperature (580-600 °C) as shown in Fig.…”

“…This was possibly that dealumination increased Ni dispersion. The presence of stronger interaction between nickel oxide and dealuminated beta zeolite to reduce NiO particle size [59]. The X-ray diffraction patterns (Fig.…”

“…This was possible that the interaction between Ni particles and surface of desilicated zeolite was lower resulting in the smaller degree of Ni dispersion from 1.67% to 0.35-0.93%. [59,61]. Whereas, the reduction temperature at 560 ˚C was assigned as the reduction of Na + ion.…”

“…It exhibited that the reduction temperature of Ni catalysts supported on dealuminated zeolite was shifted to the higher temperature from 560 °C (Ni/beta catalyst) to 660 °C (Ni/beta-0.25M-deA catalyst). The reduction temperature at 600 °C might be the reduction of nickel aluminate (NiAl 2 O 4 ) or nickel silicate (Ni 2 SiO 4 ) specie[59,61]. For the use of the higher HF concentration (0.50-0.75 M), the higher reduction temperature which was 660 °C on Ni/beta-0.25M-deA catalyst shifted to lower temperature (580-600 °C) as shown in Fig.4.9.…”