Search

Temperature programmed reduction (TPR) analysis was used to evaluate the chemical reduction progression and carburization behavior of a molybdenum oxide (MoO3) catalyst utilizing carbon monoxide (CO) as a reductant. X-ray diffraction spectroscopy (XRD), transmission electron microscopy (TEM), and a CHNS/O elemental analyzer were used to determine the composition and morphology of the reduced phases. The reduction and carburization behaviour of MoO3 catalyst was attained up to 700 °C in a stream of 60 vol. % CO in helium. Carburization was continued with isothermal mode at 700 °C for 90 and 120 min. XRD analysis confirmed the formation of molybdenum carbide (Mo2C) at 2θ=34.49° and 61.63° after carburization for 90 min at 700°C. After prolonged the carburization process for 120 min, XRD patterns shows the increasing in intensity of Mo2C peak at 2θ=34.58°, 61.67° and 74.48°. This is consistent with the CHNS/O data which show the increasing in carbon contents from 9.8 % to 11.0 % when isothermal mode of carburization was increase from 90 min to 120 min. The TEM analysis shows the sample was surrounded by less dark layer which expecting the formation of carbon after 90 min carburization. While for carburization up to 120 min, the TEM image shows the clump densely particles against each other so that no pores are present. Hence, the CO as reducing agent able to promote the formation of Mo2C while the increasing in carburization times able to enhance the formation of carbide species. [ABSTRACT FROM AUTHOR]

The carburization behaviour of nickel molybdenum trioxide (Ni-MoO3) catalyst with different loading of Ni has been studied by using temperature programmed reduction (TPR) with exposure of 60 vol. % CO in 40 vol. % helium as a reductant. The Ni-MoO3 catalysts were prepared by using the conservative wet impregnation method. The carburization characteristics of prepared catalysts were examined by isothermal carburization mode at 700°C for 90 minutes. The carburized phases were characterized by using X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and field emission scanning electron microscopy (FESEM). XRD pattern for undoped MoO3 show the formation of molybdenum dioxide (MoO2) (2θ=37° and 74.10°) and Mo2C (2θ=33.63° and 62.50°). After addition of nickel at higher loading which is 3% (wt./wt.) of Ni-MoO3 show the XRD pattern obtained Mo2C at at 2θ=61.47°. This is showing that the higher loading of nickel in MoO3 lead to higher reducibility compared 1% (wt./wt.) of Ni-MoO3 but the broad and weak peak resulted from XRD pattern. By calculating the crystallites size 7.11 nm for 3% (wt./wt.) Ni-MoO3 catalyst give the higher crystallinity compared to 1% (wt./wt.) Ni-MoO3 catalyst which is 5.70 nm. Physical analysis by using BET showed an increasing in surface area and pore size of MoO3 catalyst after addition of Ni metal loading. This proves that the higher the addition of loading might attribute to the increasing in active site for enhancing the carburization process which lead to the formation of Mo2C. The slightly phase covering the surface of the particles or seemed like an agglomerate is amorphous deposited carbon that formed between the platelet shape on Ni-MoO3 surfaces were observed through the FESEM images indicating some morphology modification occurred on MoO3. Based on these results, it is interesting to address that the addition of Ni metal to MoO13 has a remarkable influence in carburization process. The 3% (wt./wt.) of Ni on MoO3 catalyst was sufficient to promote the formation of Mo2C. [ABSTRACT FROM AUTHOR]

The development of environmentally friendly materials and composites keeps growing interest from various industries and one of that is in polymer composites processing. The production of polymer composites with nanocellulose as a reinforcement material is currently a hot research area, owing to the superior properties of nanocellulose itself. Research on nanocellulose composites have made significant contributions to the development of functional and sustainable materials for various applications such as packaging, building and construction material, automotive, aerospace, and biomedical. The presence of nanocellulose in composites is usually affected the mechanical properties like tensile strength, flexural strength and impact strength. Besides that, there are several factors that can affect the mechanical properties of nanocellulose composites such as fiber loading, distribution, orientation and the use of compatibilizers. Thus, this article provides an extensive overview on the effect of nanocellulose on the mechanical performance of polymer composites. Besides, several factors that contributed in the production of an excellent mechanical properties of nanocellulose composites were also tackled. [ABSTRACT FROM AUTHOR]

This paper presents a new sensing material derived from carbon nanofibers (CNF) functionalized with carboxylic acid first, before further modified with amide functional group. This sensing material was used in the detection of ammonia gas at room temperature. Modified CNF was prepared via Fischer Esterification using dodecylamine as functionalizing reactant. The modified CNF was characterized by field emission-scanning electron microscopy attachment with energy dispersive X-ray (FESEM-EDX) analysis to confirm the attachment of carboxylic and amide functional group. Based on characterization result, CNF successfully modified with the carboxylic and amide functional group by exhibit alteration in their morphology and elemental composition. Then, modified CNF was deposited on interdigitated transducer (IDT) by drop casting method and placed in a customized chamber with electrical feed through occupied with outlet/inlet gas. The resistance of modified CNF upon injection of ammonia gas was monitored with a digital multimeter and compared with the resistance of pristine CNF. Based on the result, modified CNF showed a better response and higher sensitivity than pristine CNF at room temperature. [ABSTRACT FROM AUTHOR]