Waste apple pomace conversion to acrylic acid: Economic and environmental assessment

The global demand for acrylic acid (AA) is increasing due to its wide range of applications. Due to this growing demand, alternative AA production strategies must be explored to avoid the exacerbation of prevailing climate and global warming issues since current AA production strategies involve AA production using fossil resources. Investigations on alternative strategies for AA production therefore constitute an important research interest. The present study therefore assesses waste apple pomace (WAP) as a feedstock for the sustainable AA produc-tion. To undertake this assessment, process models, based on two production pathways were designed, modelled and simulated in ASPEN plus® software. The two competing production pathways investigated include a process incorporating WAP conversion to lactic acid (LA), prior to LA dehydration to generate AA (denoted as the FD pathway) and another process involving WAP conversion to propylene, prior to propylene oxidation to generate AA (denoted as the TFO pathway). Economic and environmental performances of the FD and TFO pathways were assessed via the minimum selling price (MSP) and potential environmental impacts per h (PEI/h) metrics. The study was able to show that the FD pathway presented an improved economic performance (MSP of AA: US $1.17 per kg) performance compared to the economic performance (MSP of AA: US $1.56 per kg) of the TFO pathway. Crucially, the TFO process was shown to present an improved environmental performance (2.07 kPEI/h) compared to the environmental performance of the FD process (8.72 kPEI/h). These observations sug-gests that the selection of the preferred AA production will require a trade-off between the performance measures, and the integration of a multi-criteria decision assessment in future work.

Influence of Cobalt Substitution in LaMnO3 on Catalytic Propylene Oxidation

Perovskite-type structures LaBO3 with the compositions of LaMn1-xCoxO3 (x = 0.0, 0.3, 0.5, 0.7, and 1.0) were synthesized at 800 °C by a modified co-precipitation precursor technique for total oxidation of propylene, as a model test of the hydrocarbon oxidation reaction. Details concerning the evolution of the crystal structure, morphology, and crystallite size were performed by X-ray diffraction (XRD), Thermo Gravimetry Analysis (TGA)/Differential Scanning Calorimetry (DSC), Fourier Transform Infra-Red (FTIR), Atomic Absorption Spectroscopy (AAS), Scanning Electron Microscopy (SEM), and Electron Spin Resonance (ESR) techniques. All compositions were identified to be single-phase and are indexed to rhombohedral structures. TG/DSC technique evidenced a temperature of 330 °C needed for the precursor as the start point and 800 °C completion for perovskite phase formation. Slight distortion in XRD diffraction peaks was observed on substituting manganese with cobalt in B-site, and new peaks emerged. An attempt has been made to understand the effect of the B-site substitution of Co3+ ions in the lattice of LaMnO3 and their influence on catalytic total propylene oxidation efficiency. These compounds show a considerable increase in the activity of propylene oxidation to carbon dioxide and water and could be explored for hydrocarbon pollution control.

Influence of Cobalt Substitution in LaNiO3 Nanoperovskite on Catalytic Propylene Oxidation

Perovskite-type oxides with transition elements offer promising potential as catalysts in total oxidation reactions. The present work reports the synthesis of crystalline lanthanum nickelates and cobaltates and their intermediate nanomaterials compositions LaNi1-XCoXO3 (x = 0.3, 0.5, and 0.7) at 800 ºC by co-precipitation precursor technique for structural, morphological, and total propylene oxidation catalytic activity. The evolution of the crystal structure and formation of the perovskite phase were analyzed by X-ray diffraction, Thermo Gravimetry Analysis (TGA) / Differential Scanning Calorimetry (DSC), Fourier Transformed Infra-Red (FTIR), Atomic Absorption Spectroscopy (AAS), Scanning Electron Microscopy (SEM), Brunauer–Emmett–Teller (BET), Electron Spin Resonance (ESR) techniques. The terminal compounds LaNiO3, LaCoO3, and their intermediates compositions were identified to be single-phase and are indexed to rhombohedral structures. The bonding characteristics were studied by FTIR spectroscopy. On substitution of Ni with Co in B-site, the slight distortion in XRD diffraction peaks were observed. These compounds show a considerable increase in the activity of propylene oxidation to carbon dioxide. This study aims at understanding the effect of B– site substitution in the lattice of LaNiO3 and their influence on catalytic propylene oxidation efficiency.