Superior Long-Term Stability of a Mesoporous Alumina-Supported Pt Catalyst in the Hydrodeoxygenation of Palm Oil

Abstract

Catalyst stability in the hydrodeoxygenation of vegetable oils is one of the big challenges for practical production of bio-jet fuel. Particularly, supported Pt catalysts are known to show activity decay because of Pt sintering and coking. Herein, we report superior long-term stability of the Pt catalyst in the hydrodeoxygenation of palm oil by using the mesoporous γ-Al2O3 (MA) support synthesized by solvent-deficient precipitation (SDP). When the MA was prepared with a molar ratio of water to aluminum isopropoxide being five, the space-time yield of the Pt catalyst was maintained at ca. 6.09 mol kg–1 h–1 for over 80 h, which was much better than those of the other Pt catalysts. This result was attributed to the two properties such as well-developed mesopores of a larger diameter than 20 nm in the fresh MA and strong metal–support interaction of Pt/MA. Therefore, the SDP method could endow the alumina support with textural and chemical benefits for stable performance. Furthermore, the hydrodeoxygenated palm oil was converted into paraffinic hydrocarbons mainly ranging from C8 to C15 with an iso- /n-paraffin ratio of ca. 6.8, perfectly meeting the standard specifications of bio-jet fuel.

Mesoporous Acidic SiO2–Al2O3 Support Boosts Nickel Hydrogenation Catalysis for H2 Storage in Aromatic LOHC Compounds

“…This is closely associated with the nearly identical crystallinity of γ-Al 2 O 3 (Figure S16), textural properties (Table S3 and Figure S17), and the corresponding similar D Ni (Figure S18) of the fresh and spent Ni catalysts, indicating the excellent structural prepared by the SDP method. 35 Additionally, the catalytic activity and stability of Ni/MA and Ni/MSA_C 8 TES were evaluated using a fixed-bed reactor operated at 200 °C and 16 h −1 WHSV, which were selected from preliminary experiments to clearly notice activity change with respect to time-on-stream. The higher hydrogenation activity of Ni/MSA_C 8 TES than Ni/MA was also confirmed in these continuous runs.…”

“…Additionally, continuous experiments were performed using a downflow trickle-bed reactor (10 mm inner diameter and 380 mm length) described before. , The reactor was heated to 200 °C in a H 2 flow and pressurized to 40 bar H 2 , which was maintained during the entire run. Then, H 0 -MBT was fed through a preheater (80 °C) to the reactor in which the weight hourly space velocity (WHSV) and the H 2 /H 0 -MBT mole ratio were adjusted to 16 h –1 and 20, respectively.…”

“…The X H0-MBT , product selectivities (S Hx-MBT ), and DoH l were estimated from the GC results of liquid samples obtained in batch mode A, while DoH g in batch mode B, equivalent to the conversion of H 2 (X Hd 2 ), was calculated from the moles of H 2 present in the gas buret, as follows Additionally, continuous experiments were performed using a downflow trickle-bed reactor (10 mm inner diameter and 380 mm length) described before. 11,35 The reactor was heated to 200 °C in a H 2 flow and pressurized to 40 bar H 2 , which was maintained during the entire run. Then, H 0 -MBT was fed through a preheater (80 °C) to the reactor in which the weight hourly space velocity (WHSV) and the H 2 /H 0 -MBT mole ratio were adjusted to 16 h −1 and 20, respectively.…”

“…33,34 The MA was also reported to show improved metal dispersion and catalyst stability by strong metal−support interaction. 35 Moreover, the addition of SiO 2 into MA was achieved by initially mixing AIP with TEOS 36 or octyltriethoxysilane (C 8 TES). 37 These reports intrigued us to try synthesizing the SiO 2 −Al 2 O 3 by the SDP method using AIP and C n TES with different lengths of the alkyl substituent because the alkyl substituent affects the ratio of condensation and cyclization rates in sol−gel synthesis.…”

“…The properties of SiO 2 –Al 2 O 3 , including textural and acidic characteristics, generally depend on the synthesis method. In this respect, solvent-deficient precipitation (SDP) is interesting because it can provide significant mesoporosity without addition of structure-directing agents, e.g., mesoporous alumina (MA) synthesized using aluminum isopropoxide (AIP). , The MA was also reported to show improved metal dispersion and catalyst stability by strong metal–support interaction . Moreover, the addition of SiO 2 into MA was achieved by initially mixing AIP with TEOS or octyltriethoxysilane (C 8 TES) .…”