Comparison of Cr/C and Cr2O3/Z Catalysts on Hydrocracking of Bio Oil from Pyrolysis of Palm Empty Fruit Bunches

Bio-oil derived from palm empty fruit bunch is not suitable for fuel purpose due to high acidity and low heating. Cr2O3/Zeolite and Cr/C catalysts was developed to upgrade bio-oil through hydrocracking. The catalyst prepared via impregnation method followed by oxidation-reduction. Ammonia and pyridine adsorption used to evaluate acidity as well as crystallinity assessment by using XRD. Hydrocracking reaction conducted in hydrogen gas flow rates 0.5-3.0 L/min, the surface area of Cr/C catalyst found out 1,497.07-1,652.58 m2/g, whilst the temperatures 450 to 700 ℃ and the catalyst weights between 0.5 to 2.5 g. Acidity calculated from ammonia and pyridine adsorption shows Cr2O3/Zeolite has higher value compare to pristine Zeolite. XRD pattern shows Cr2O3/Zeolite has high crystallinity as indicated by sharp and pointed diffraction peaks. The optimum condition of hydrocracking confirmed by lower density of liquid product. The variables obtained by a separate experiments shows that H2 gas flow rate best at 2.5 L/min, temperature of hydrocracking 500 ℃ for Cr2O3/Zeolite and 600oC for Cr/C whereas weight of Cr2O3/Zeolite catalyst is 1.5 g. The Cr/C catalyst that gave low density product possess 1,554.48 m2/g surface area. GCMS data shows increase on the number of straight chain compounds within the hydrocracking product.

Dehydration of Fructose to 5-Hydroxymethylfurfural: Effects of Acidity and Porosity of Different Catalysts in the Conversion, Selectivity, and Yield

There is a demand for renewable resources, such as biomass, to produce compounds considered as platform molecules. This study deals with dehydration of fructose for the formation of 5-hydroxymethylfurfural (HMF), a feedstock molecule. Different catalysts (aluminosilicates, niobic acid, 12-tungstophosphoric acid—HPW, and supported HPW/Niobia) were studied for this reaction in an aqueous medium. The catalysts were characterized by XRD, FT-IR, N2 sorption at −196 °C and pyridine adsorption. It was evident that the nature of the sites (Brønsted and Lewis), strength, quantity and accessibility to the acidic sites are critical to the conversion and yield results. A synergic effect of acidity and mesoporous area are key factors affecting the activity and selectivity of the solid acids. Niobic acid (Nb2O5·nH2O) revealed the best efficiency (highest TON, yield, selectivity and conversion). It was determined that the optimum acidity strength of catalysts should be between 80 to 100 kJ mol−1, with about 0.20 to 0.30 mmol g−1 of acid sites, density about 1 site nm−2 and mesoporous area about 100 m2 g−1. These values fit well within the general order of the observed selectivity (i.e., Nb2O5 > HZSM-5 > 20%HPW/Nb2O5 > SiO2-Al2O3 > HY > HBEA).

Nonthermal Plasma Induced Fabrication of Solid Acid Catalysts for Glycerol Dehydration to Acrolein

The feasibility of fabricating better solid acid catalysts using nonthermal plasma (NTP) technology for biobased acrolein production is demonstrated. NTP discharge exposure was integrated in catalyst fabrication in air or argon atmosphere. The fabricated catalysts were characterized by Brunauer–Emmett–Teller surface area analysis, temperature-programmed desorption of ammonia, X-ray powder diffraction and Fourier-transform infrared spectroscopy of pyridine adsorption, in comparison to regularly prepared catalysts as a control. Further, kinetic results collected via glycerol dehydration experiments were compared, and improvement in acrolein selectivity was displayed when the catalyst was fabricated in the argon NTP, but not in the air NTP. Possible mechanisms for the improvement were also discussed.

Adsorption of pyridine from aqueous solutions onto polyaluminium chloride and anionic polyacrylamide water treatment residuals

The adsorption performance of pyridine onto polyaluminium chloride (PAC) and anionic polyacrylamide (APAM) water treatment residuals (WTRs) was investigated by batch experiments. This study confirmed the assumption that PAC–APAM WTRs had the ability to remove pyridine. The non-linear Dubinin–Radushkevich model and non-linear Freundlich model better described the isotherms, indicating that the adsorption was a chemically controlled multilayer process. The pyridine adsorption rate was simultaneously controlled by external film diffusion and intraparticle diffusion. The adsorption of pyridine was an endothermic reaction with randomness increase. The pyridine adsorption decreased with pH increase. Pyridine removal was observed to be a linear increase from 6.16% to 96.18%, with the increase of dosage from 2.5 g/L to 15 g/L. The Langmuir maximum adsorption capacity was 3.605 mg/g while the theoretical isotherm saturation capacity was 9.823 mg/g. Therefore, PAC–APAM WTRs recycled into contaminated soils for remediation is expected to be an innovative alternative disposal method. More research is recommended in the future to identify detailed adsorption mechanisms and the most appropriate mixing ratio of PAC–APAM WTRs to contaminated soils under various climatic conditions.

Acid Properties of GO and Reduced GO as Determined by Microcalorimetry, FTIR, and Kinetics of Cellulose Hydrolysis-Hydrogenolysis

Graphene oxide addresses increasing interests as a solid acid catalyst working in water for carbohydrate conversion. If there is a general agreement to correlate its unique catalytic performances to its ability to adsorb sugars, the origin of its acidity remains controversial. In this article, we study the acid strength of graphene oxide (GO) prepared by modified Hummers method and that of reduced GO by calorimetry of NH3 adsorption and by FTIR of pyridine adsorption. Very strong acid sites are detected on GO by calorimetry, while reduced graphene oxide (reGO) is not very acidic. The FTIR of pyridine adsorption shows the prevailing presence of Br∅nsted acid sites and a unique feature, the presence of pyridine coordinated by hydrogen bonds. This exceptionally strong Br∅nsted acidity is tentatively explained by the presence of graphene domains decorated by hydroxyl, carboxylic, or sulfonated groups within the GO sheet, resulting in a high mobility of the negative charges which makes the proton free and explains its strong acidity. Accordingly, only GO is active and selective for native cellulose hydrolysis, leading to 27% yield in glucose. Finally, we show that sugar alcohols cannot be formed directly from cellulose using GO combined with Pt/re-GO under hydrogen, explained by the reduction of oxygenated functions of GO. The instability of the functional groups of GO in a reducing atmosphere is the weak point of this peculiar solid acid.

Comparison of Lewis Acidity between Al-MCM-41 Pure Chemicals and Al-MCM-41 Synthesized from Bentonite

This study focused on the Lewis acidity of Al-MCM-41 prepared from bentonite (Al-MCM-bentonite) as silica and aluminum source simultaneously. This acidity was compared with Al-MCM-41 synthesized from pure chemicals reagents (Al-MCM-standard). Structural analysis showed that the substitution of the silicon atom by the aluminum atom decreases the structural order of Al-MCM-standard, whereas Al-MCM-bentonite has a better structural organization. The Lewis acidity of the Al-MCM-bentonite was evaluated in allylation reaction of benzaldehyde with allyltrimethylsilane and pyridine adsorption experiments. The results showed that the difference in acidity between Al-MCM-standard and Al-MCM-bentonite is due to the amount of aluminum incorporated into the framework of our mesoporous materials. According to the EDX analysis, the incorporation of aluminum in Al-MCM-standard (Si/Al = 13.47) is more important than in Al-MCM-bentonite (Si/Al = 43.64). This explains the low acidity of Al-MCM-bentonite, and the moderate yields in the allylation reactions of benzaldehyde with allyltrimethylsilane. Copyright © 2019 BCREC Group. All rights reserved