Tailoring the surface area and the acid–base properties of ZrO2 for biodiesel production from Nannochloropsis sp.

Abstract

Bifunctional heterogeneous catalysts have a great potential to overcome the shortcomings of homogeneous and enzymatic catalysts and simplify the biodiesel production processes using low-grade, high-free-fatty-acid feedstock. In this study, we developed ZrO2-based bifunctional heterogeneous catalysts for simultaneous esterification and transesterification of microalgae to biodiesel. To avoid the disadvantage of the low surface area of ZrO2, the catalysts were prepared via a surfactant-assisted sol-gel method, followed by hydrothermal treatments. The response surface methodology central composite design was employed to investigate various factors, like the surfactant/Zr molar ratio, pH, aging time, and temperature on the ZrO2 surface area. The data were statistically analyzed to predict the optimal combination of factors, and further experiments were conducted for verification. Bi2O3 was supported on ZrO2 via the incipient wetness impregnation method. The catalysts were characterized by a variety of techniques, which disclosed that the surfactant-assisted ZrO2 nanoparticles possess higher surface area, better acid–base properties, and well-formed pore structures than bare ZrO2. The highest yield of fatty acid methyl esters (73.21%) was achieved using Bi2O3/ZrO2(CTAB), and the catalytic activity of the developed catalysts was linearly correlated with the total densities of the acidic and basic sites. The mechanism of the simultaneous reactions was also discussed.

Micro‐structural Analysis and Photocatalytic Properties of Green Synthesized t‐ZrO2 Nanoparticles

“…Figure 8 and Table 3 show the BET surface area of t‐ZrO 2 NPs prepared by green method. The obtained BET surface area is 38 m 2 /g and single point surface area at P/P 0 value of 0.30 is found to be 49.90 m 2 /g which matches with other similar reported values [32,33] . The surface area related with average equivalent particle size is given by the relation D BET =6000/(ρ.Sw)(in nm), where D BET is the average diameter , Sw represents surface area of the NPs in m 2 /g and ρ is the theoretical density in g/cm 3 .…”

Synthesis of diethyl carbonate from ethanol and CO2 over ZrO2 catalysts

“…In the TPD-NH 3 profiles two peaks can be distinguished in the 373-423 K and 673-873 K range, which correspond to weak and strong acid sites, respectively, while the species desorbing between these peaks correspond to acid sites of medium strength (Rahman et al 2019). The effects of impregnating Na and Mg in the catalyst acidity of ZrO 2 -873 K are shown in Fig.…”

Recent developments in layered double hydroxide structures with their role in promoting photocatalytic hydrogen production: A comprehensive review

“…It has been denoted that the incorporation of Co 2+ into the brucite layer of LDH could improve the surface area of the LDH, which is in parallel with the study performed by Jawad et al 167 They highlighted that increasing the Co 2+ content until its optimal amount essentially enhances the surface area of the Co-LDH, which is beneficial for inhibiting the oxides/hydroxides from agglomeration. 168 This can be attributed to the large ionic radii exhibit by Co 2+ (0.072 nm) compared to other divalent metal ions. Besides, the dispersion of Co species in the LDH precursor remarked an enhancement in the redox activity with robust stability as they were observed to exhibit no ionic leaching during the degradation process.…”