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RISS 인기검색어
- 검색키워드
- 저자 : Ahmad Zuhairi Abdullah (검색결과 5 건)
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Ahmad Zuhairi Abdullah,Muhammad Hazim Yaacob,Nor Irwin Basir 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.85 No.-
Single-step selective catalytic dehydrogenation of glycerol to lactic acid requires a catalyst with strongdehydrogenation and hydration capabilities. A multi-component catalyst consisting of an alkaline earthmetal and assisted by a transition metal is deemed essential to achieve yield lactic acid in this multi-stepreaction. A series of NiO/CaO catalysts with different Ni/Ca ratios were synthesized via a co-precipitationmethod and tested for their catalytic activity. The physicochemical properties of the catalysts werestudied through TGA, SEM, N2-adsorption, CO2-TPD and XRD analyses. The NiO particles were relativelysmaller than those of CaO to enable their deposition on the surface of the latter. High amounts of basicsites of more than 4.84 mmol/gcat were detected on the NiO/CaO catalysts. The lactic acid yield wasstrongly influenced by the molar ratio of the NiO/CaO catalysts due to their improved dehydrogenationand hydration capabilities. The synergy between NiO with CaO in the catalyst was also elucidated. The0.43NiO/CaO catalyst exhibited desirable activity with 41.4% lactic acid yield at 89.3% glycerol conversion. A catalyst loading of 15 wt. %, a reaction temperature of 290 C and 1.5 h of reaction time were needed toachieve this conversion. Thus, the combination of NiO/CaO resulted in the synergy towards achievingbetter lactic acid yield in this selective conversion to lactic acid. However, accurate control of the reactionwas critical as the intermediates and lactic acid were highly reactive to participate in other side-reactions.
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A review on one-pot synthesis of acrylic acid from glycerol on bi-functional catalysts
Muhammad Yusri Ahmad,Nor Irwin Basir,Ahmad Zuhairi Abdullah 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.93 No.-
Oxydehydration is one of the possible reactions to valorize glycerol to acrylic acid that has high demandin industry. Glycerol oxydehydration is a two-step reaction that is an interesting, yet challengingapproach to give high acrylic acid yield. The reaction consists of the dehydration to 3-hydroxypropanaland subsequently to acrolein catalyzed by mainly Brønsted acid sites. Selective oxidation catalyzed bymetal sites should then be carried out to form acrylic acid. A single-step or one-pot conversion requires amulti-component catalyst addressing the requirements of both steps to selectively form the desiredproduct. Strong acid sites will catalyze the undesired glycerol oxidation reactions while metals with highredox capability tend to cause oxidative decomposition of acrolein. This work reviews the recent workson glycerol catalytic oxydehydration to form acrylic acid in a one-pot approach. The complete reactionmechanism and specific requirements are elucidated. Main focus is given to the pros and cons of fourgroups of catalysts i.e. vanadium pyrophosphates, supported heteropoly acids, mixed metal oxides andmolecular sieves. The roles of specific acid sites, type and composition of active components and redoxstrength of active components are critically reviewed.
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Mohammad Aslam,Ahmad Zuhairi Abdullah,Mohd Rafatullah 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.98 No.-
Nanoparticles (NPs) have properties for potential applications in different areas but their conventionalproduction processes are often linked to secondary health and environmental impacts. Aggressiveresearch endeavors are being undertaken to identify greener NPs synthesis strategies. Green synthesis isan evolving area with the objective of an efficient and environmental friendly development of NPs. Biological substances including bacteria, fungi, yeast, algae, and plant have been demonstrated to beapplicable for the synthesis of TiO2 NPs. This work is dedicated to phyto-based biosynthesis of TiO2 NPs. Biomolecules in plants such as terpenoids,flavones, ketones, aldehydes, proteins, amino acids, vitamins,alkaloids, tannins, phenolics, saponins, and polysaccharides can play vital roles as a reducing, cappingand stabilizing agent in the formation of TiO2 NPs. A systemic comparison is made with the focus on thebioreduction ability of different plant extracts to produce specific TiO2. Important results of applicableinstrumentation techniques for characterizing the TiO2 NPs are also elucidated to identify the superiorqualities of the NPs. Moreover, photocatalytic and antimicrobial applications of the phytosynthesizedTiO2 NPs are also critically discussed. The main scopes are the current status of plant- assistedbiosynthesis of TiO2 NPs and future prospects of this promising area of research.
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Pengyong Hoo,Ahmad Zuhairi Abdullah 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.4
Process optimization of selective esterification of glycerol with lauric acid catalyzed by highly uniformed SBA-15 catalysts post impregnated with 12-tungstophosphorus acid (HPW) has been elucidated via response surface methodology (RSM). The significance of factors including reaction time (t), reactants ratio (R) and temperature (T) was investigated and led to the development of response models for lauric acid conversion (R1) and monolaurin yield (R2). The optimized monolaurin yield operating condition (50% yield at t=3.18 h, R=4.6 and T=175 oC) was identified by using the developed models with high accuracy (98% confidence level, small standard deviation and error) and reproducibility (3 times). Comparison done with reported results showed the good performance of developed catalyst with significant reduction in reaction time needed to achieve similar lauric acid conversion and monolaurin yield.
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Mohd Hizami Mohd Yusoff,Ahmad Zuhairi Abdullah 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.2
Sulfated zirconia supported on SBA-15 (SZSBA-15) catalysts with different zirconia loadings (5-20 wt%) were synthesized using urea hydrolysis method. Effects on the physicochemical properties of the catalysts and activity in selective glycerol esterification with palmitic acid were particularly investigated. Various characterization techniques such as N2 adsorption-desorption analysis, SEM, TEM, TGA, FTIR, NH3-TPD and acidity measurement by titration were used. Increasing zirconia loading decreased the surface area, pore size and pore volume of the catalysts, but increased the sulfate content and improved the catalyst acidity. Larger surface area was not the major factor in determining the catalyst activity especially in the reaction involving bulky molecules. The reaction was found to be influenced by the amount of active sites presence on the catalyst and also by the dimension of the pores which slightly promoted the shape selective reaction. Among all catalyst, 15SZSBA-15 demonstrated the highest activity with 88% conversion and 44% monopalmitin yield.
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