Pt/SAPO-11 Catalysts: Effect of Platinum Loading Method on the Hydroisomerization of n-Hexadecane

Pinpointing basic sites formed upon incorporation of iron in hierarchical SAPO-11 using catalytic model reactions

By utilizing previously established catalytic model reactions, a method for probing the topological location of transition metal sites incorporated in hierarchical silicoaluminophosphates (SAPOs) is presented. For the first time, iron(III)-incorporated hierarchical SAPO-11 (FeCTAB-11) was prepared and thoroughly characterized with conventional iron(III)-incorporated SAPO-11 (FeSAPO-11) as a reference. Initially, inductively coupled plasma - mass spectrometry (ICP-MS) indicated that the FeSAPOs contained similar amounts of metal (∼2.0 wt%), while N₂-physisorption confirmed the bimodal porosity of the hierarchical FeCTAB-11. Furthermore, X-ray absorption spectroscopy (XAS) revealed that iron(III) was isomorphously incorporated into both SAPO-11 samples, whereas CO₂-temperature programmed desorption (TPD) revealed the first reported presence of strong basic sites in the vicinity of a transition metal incorporated into a SAPO framework. The location of the basic sites, and thus the incorporated iron, was subsequently probed by studying the products of the base-catalyzed vapor phase isomerization of cyclohexanone oxime (Beckmann rearrangement, BMR) model reaction. Through an increased lifetime for the base-catalyzed production of aniline, the incorporated iron for FeCTAB-11 was found to be located in highly accessible mesopores, whereas the conventional FeSAPO-11 had incorporated iron located in its micropores. Lastly, the methanol-to-hydrocarbons (MTH) model reaction showed that both FeSAPOs only had Brønsted acid sites in the micropores of the structures. This was used to verify the pore connectivity of the hierarchical FeCTAB-11 by utilizing the base-catalyzed BMR mechanism's dependency on acid sites.

Synthesis of mesoporous Pt@SAPO-11 via in situ encapsulation for the decarboxylation of oleic acid to prepare C8–C17 alkanes

The 1.0 wt% Pt@SAPO-11 catalyst was prepared by an in situ encapsulation method and used to catalyze the decarboxylation of oleic acid to C8–C17 alkanes. A reaction yield of 80.8% was achieved after 4 h at 340 °C.

Effect of Water and Glycerol in Deoxygenation of Coconut Oil over Bimetallic NiCo/SAPO-11 Nanocatalyst under N2 Atmosphere

The catalytic deoxygenation of coconut oil was performed in a continuous-flow reactor over bimetallic NiCo/silicoaluminophosphate-11 (SAPO-11) nanocatalysts for hydrocarbon fuel production. The conversion and product distribution were investigated over NiCo/SAPO-11 with different applied co-reactants, i.e., water (H₂O) or glycerol solution, performed under nitrogen (N₂) atmosphere. The hydrogen-containing co-reactants were proposed here as in-situ hydrogen sources for the deoxygenation, while the reaction tests under hydrogen (H₂) atmosphere were also applied as a reference set of experiments. The results showed that applying co-reactants to the reaction enhanced the oil conversion as the following order: N₂ (no co-reactant) < N₂ (H₂O) < N₂ (aqueous glycerol) < H₂ (reference). The main products formed under the existence of H₂O or glycerol solution were free fatty acids (FFAs) and their corresponding C_n−1 alkanes. The addition of H₂O aids the triglyceride breakdown into FFAs, whereas the glycerol acts as hydrogen donor which is favourable to initiate hydrogenolysis of triglycerides, causing higher amount of FFAs than the former case. Consequently, those FFAs can be deoxygenated via decarbonylation/decarboxylation to their corresponding C_n−1 alkanes, showing the promising capability of the NiCo/SAPO-11 to produce hydrocarbon fuels even in the absence of external H₂ source.