Importance of Size and Distribution of Ni Nanoparticles for the Hydrodeoxygenation of Microalgae Oil

Abstract

Improved synthetic approaches for preparing small-sized Ni nanoparticles (d=3 nm) supported on HBEA zeolite have been explored and compared with the traditional impregnation method. The formation of surface nickel silicate/aluminate involved in the two precipitation processes are inferred to lead to the stronger interaction between the metal and the support. The lower Brønsted acid concentrations of these two Ni/HBEA catalysts compared with the parent zeolite caused by the partial exchange of Brønsted acid sites by Ni(2+) cations do not influence the hydrodeoxygenation rates, but alter the product selectivity. Higher initial rates and higher stability have been achieved with these optimized catalysts for the hydrodeoxygenation of stearic acid and microalgae oil. Small metal particles facilitate high initial catalytic activity in the fresh sample and size uniformity ensures high catalyst stability.

High-grade diesel production by hydrodeoxygenation of palm oil over a hierarchically structured Ni/HBEA catalyst

“…10 In addition, the C TPAOH /C OH -1 ratio was altered from 0, 0.3, 0.6, 0.9, to 1.0 at 65 ºC for 190 min., in order to test the influence of TPAOH concentrations towards HBeta support. Such improved catalyst led to a high 40 conversion rate of 67 mmol -1 g -1 h -1 (equivalent to 19 g·g -1 ·h -1 ), which is far beyond the reported best results (14 mmol·g -1 ·h -1 , equivalent to 5 g·g -1 ·h -1 ) on Ni/HBeta [18] . By contrast, the pure NaOH or TPAOH treated HBeta supported Ni nanoclusters catalyzed relatively lower hydrocarbon yields than the 20 TPAOH/NaOH mixture (see Figure 4b), implying that desilication needs collaboration of weak and strong alkali to exert cooperative remarkable performance.…”

“…-1 ·h -1 ) [18] . However, the current techniques even with the best Ni/HBEA catalyst are far below the requirement of lipid upgrading in a large scale out of laboratory tests.…”

Development of nickel based catalysts for the transformation of natural triglycerides and related compounds into green diesel: a critical review

“…Actually, there is only one important contribution dealing systematically with the influence of preparation method, limited in the context of impregnation techniques, on the catalytic performance of nickel metallic catalysts. This was reported by the Lercher group [132]. Continuing their work on the nickel catalysts supported on zeolites [110] they prepared four 5%HBEA catalysts using conventional incipient wetness impregnation, ion-exchange/precipitation (actually "equilibrium deposition filtration" at relatively high pH favoring deposition by surface precipitation [133]), deposition precipitation (DP) using ammonia as precipitating agent [134] and grafting of as-synthesized Ni nanoparticles (Ni NP) [135].…”

Quantitative conversion of triglycerides to hydrocarbons over hierarchical ZSM-5 catalyst

“…During the hydrotreating process, the support of catalyst plays a significant role in the whole reaction. Nowadays, many materials like SiO 2 , TiO 2 , SAPO-11, HBEA and ZSM-22 have been used as the supports for the hydroconversion of vegetable oil to hydrocarbons [23][24][25][26]. Recently, considerable attention has been paid to hierarchical materials in catalysis application [27][28][29][30].…”