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A major cause of premature catalyst deactivation in the catalytic hydrogenation of fatty acids is the presence of impurities in the feedstock. With more oleochemical plants shifting to opportunistic crude palm oil (CPO) as their feedstock, the feedstock quality becomes an important factor in their procurement process. For CPO, the impurities level can be coarsely estimated by the deterioration of bleaching index (DOBI). A high DOBI value (e.g. DOBI > 2.99) indicates good quality CPO and ease in processing, while low DOBI value implies low level of carotene and/or high level of oxidised sludge oil, both of which could be detrimental to the processing of CPO. In our work, unsplit CPO feedstocks with varying DOBI value were directly hydrogenated in a laboratory‐scale pressure reactor with the presence of commercial nickel catalysts. Experimental results showed that catalyst deactivation was linked to DOBI value, where decreasing DOBI led to faster catalyst deactivation. For example, iodine value (IV) < 1.0 can be achieved for CPO with high DOBI value (2.97) after 150 min, and IV of 5–7 and IV > 20 were achieved for medium DOBI value (2.57–2.68) and low DOBI value (2.24), respectively. For CPO with low DOBI value (2.24), doubling the catalyst dosage ensured that the hydrogenated product met the low IV specification. This work showed that identifying the CPO with DOBI value presents an indicator to the manufacturer to find the right CPO tailored to the existing processes to maximise profitability. [ABSTRACT FROM AUTHOR]

A series of 1, 3, and 5% Bi‐doped vanadium phosphate catalyst catalysts were prepared via sesquihydrate route using direct ultrasound method and were denoted as VPSB1, VPSB3, and VPSB5, respectively. These catalysts were synthesized solely using a direct ultrasound technique and calcined in a n‐butane/air mixture. This study showed that catalyst synthesis time can be drastically reduced to only 2 hr compared to conventional 32–48 hr. All Bi‐doped catalysts exhibited a well‐crystallized (VO)2P2O7 phase. In addition, two V5+ phases, that is, β‐VOPO4 and αII‐VOPO4, were observed leading to an increase in the average oxidation state of vanadium. All catalysts showed V2p3/2 at approx. 517 eV, giving the vanadium oxidation state at approx. 4.3–4.6. Field‐emission scanning electron microscopy micrographs showed the secondary structure consisting of thin and small plate‐like crystal clusters due to the cavitation effect of ultrasound waves. VPSB5 showed the highest amount of oxygen species removed associated with the V5+ and V4+ species in temperature‐programmed reduction in H2 analyses. TheX‐ray absorption near edge structure (XANES) measurement showed the occurrence of vanadium oxide reductions in hydrogen gas flow, indicating the presence of V4+ and V5+ species. Higher average valence states of V5+, indicating more V5+ phases, were present. The addition of bismuth has increased the activity and selectivity to maleic anhydride. [ABSTRACT FROM AUTHOR]

This paper studies the effect of addition of Zn and ultrasound-assisted co-precipitation on Cu-Mn oxide catalysts for the oxidation of CO. Cu-Mn-Zn oxide catalysts were synthesised at different molar ratios and characterised and evaluated for CO oxidation performance. Scanning electron microscopy (SEM) imaging showed that the morphologies and textural properties of the catalysts were markedly affected by the different synthesis conditions, notably the formation of different geometries of various sizes depending on the Zn loading used. Characterisation results also revealed that both the addition of Zn and the use of ultrasound-assisted synthesis improved the dispersion of metal constituents in the mixed oxide phase, evident from the lower peak intensity and smaller crystallite sizes and more dispersed particles as seen in SEM imaging. Gas adsorption results revealed that Zn loading influences the porosity and adsorption capability of the catalyst. Zn-loaded samples exhibited a H3 hysteresis loop, which suggests the presence of slit-like pores. Temperature-programmed reduction results indicate that sonicated samples exhibit improved reduction capabilities which can increase overall catalytic activity. Results showed that Cu/Mn/Zn = 2:1:0.5 displayed the highest activity, showing 76.0% and 82.8% for CO and SO2 at 130 °C, respectively. This work has confirmed that the addition of 0.5 molar ratio of Zn and the presence of ultrasonic treatment during the catalyst synthesis have improved the overall catalytic performance, while further addition in Zn concentrations resulted in an adverse effect on the catalyst. [ABSTRACT FROM AUTHOR]

• Predictions of frequency domain simulations agreed with experimental measurements. • The semi-empirical bubbly-liquid model led to more consistent simulation results. • Performance for antinode prediction showed potential for design applications. • Knowledge gaps were identified for multi-frequency sonoreactor simulation methods. Recently, multi-frequency systems were reported to improve performance in power ultrasound applications. In line with this, digital prototyping of multi-frequency sonoreactors also started gaining interest. However, the conventional method of simulating multi-frequency acoustic pressure fields in the time-domain led to many challenges and limitations. In this study, a multi-frequency sonoreactor was characterised using frequency domain simulations in 2-D. The studied system consists of a hexagonal sonoreactor capable of operating at 28, 40 and 70 kHz. Four frequency combinations were studied: 28–40, 28–70, 40–70 and 28–40–70 kHz. A semi-empirical, modified Commander and Prosperetti model was used to describe the bubbly-liquid effects in the sonoreactor. The root-mean-squared acoustic pressure was compared against experimental validation results using sonochemiluminescence (SCL) images and was noted to show good qualitative agreement with SCL results in terms of antinode predictions. The empirical phase speed calculated from SCL measurements was found to be important to circumvent uncertainties in bubble parameter specifications which reduces error in the simulations. Additionally, simulation results also highlighted the importance of geometry in the context of optimising the standing wave magnitudes for each working frequency due to the effects of constructive and destructive interference. [ABSTRACT FROM AUTHOR]