A reaction mechanism is proposed for hydrolytic dehydrogenation of ammonia borane on a Pt/CNT catalyst. A combination of thermodynamic analysis and FTIR measurement reveals that B‐containing byproducts are mainly in the form of an NH4B(OH)4‐B(OH)3 mixture rather than NH4BO2 reported previously. The revised main reaction is , involving the B–H, B–N, and O–H bond cleavages. Isotopic experiments using D2O instead of H2O as reactant or introducing D2 into the reaction atmosphere suggest the O–H bond cleavage being in the rate‐determining step, and an unfavorable occurrence of the chemisorbed H2O dissociation (i.e., the direct O–H bond cleavage), respectively. Different reaction pathways with indirect O–H bond cleavages are analyzed, and then is suggested as the rate‐determining step. Subsequently, a Langmuir–Hinshelwood kinetic model is developed, which fits well with the experimental data. © 2016 American Institute of Chemical Engineers AIChE J, 63: 60–65, 2017
BackgroundIn Ghana, fire incidents have become a regular occurrence, with thousands of lives and millions of dollars lost every year. Hardly a day passes without news of a fire outbreak in some part of Ghana, causing fear and panic among the people. This generates much discussion centering on rumors relating to politics, sabotage, misfortune, religious differences, etc. This article seeks to discuss the trend of fire incidents occurring in Ghana from 2000 to 2013 and the different ways to prevent these incidents.MethodsThe pattern of fire incidence in Ghana as a whole as well as in each region is discussed. The study took into consideration the causes, mechanisms, as well as preventive measures against the fire menace. Data were obtained from the head office of Ghana's national fire service.ResultsIt was noticed that in general the rate of fire incidence increased each year. This increase was attributed to several factors: rate of population growth and industrialization, unstable electricity, urbanization, negligence, illegal electrical connection, etc. The cause of fire was categorized into domestic, industrial, vehicular, institutional, electrical, commercial, bush, and others. Among these causes, domestic fire accounted for 41% of the total number of fire incidents in the country.ConclusionFinally, this study presents several recommendations to help prevent and mitigate fire incidents in Ghana.
Utilization of sustainable biomass to produce jet fuel range hydrocarbons is imperatively needed to mitigate CO2 emissions and to liberate the over-reliance on fossil resources. Using propanal as the feedstock, an excellent jet fuel range hydrocarbon yield (81.7%), high conversion (ca. 100%), and purity (85%) were achieved over a novel dual-bed Cu/SiO2–TiO2||Ni/ZSM-5 catalyst at low temperature and pressure in only one reactor. The intrinsic active site requirement was further investigated by multitechniques including density functional theory calculation, quantitative CO2/NH3-temperature-programmed desorption/diffuse reflectance infrared Fourier-transform spectroscopy, high-resolution transmission electron microscopy, and thermogravimetric analysis–mass spectrometry. Results showed that for the upstream bed catalyst (Cu/SiO2–TiO2), the Ti–O site pair and Ti Lewis acid site were crucial for enolate formation, carbon-chain growth, and ring closure reactions, which can be altered by the calcination temperature. The synergy between the site strength and number led to a volcanic relationship between acidity/basicity and the intermediate yield. In addition, the downstream bed Ni/HZSM-5 catalyst promoted the hydrodeoxygenation reaction toward hydrocarbon formation.
Background A woman’s ability to achieve her preferred family size is critical in addressing issues of high fertility in sub-Saharan Africa. The socio-cultural context in sub-Saharan Africa presents some difficulty for the attainment of preferred fertility for many women. Few studies in sub-Saharan Africa have examined the extent to which women are unable to achieve their preferred family sizes. This study, therefore, examines the factors that are associated with the non-attainment of women’s preferred fertility by the end of their reproductive years. Data and methods The study analyzed pooled cross-sectional data with a sub-sample of 1,888 currently married women aged 45–49 years from five rounds of the Ghana Demographic and Health Survey, 1993 to 2014. Test of associations and multinomial logistic regression analysis were used to examine the predictors of underachieved and overachieved fertility relative to achieved fertility. Results The results indicate that 44 per cent of the women recorded overachieved fertility while about 36 per cent underachieved their fertility. Partner wants more, experiencing child loss and married more than once were significantly associated with overachieved fertility. Nonetheless, increased years of a woman’s education and delaying her at first birth were negatively associated with overachieved fertility. On the other hand, underachieved fertility was significantly associated with having a partner with fewer fertility preference, being of the Islamic faith and ever use of modern contraception. Conclusion Partner’s fertility preference, child loss experience, marrying more than once and ever use of modern contraception were important predictors of a woman’s inability to achieve her fertility preference. Policies to regulate men’s fertility behaviour, delaying age at first birth, use of modern contraception, encouraging longer years of education, and reducing infant and child mortality are important strategies to achieve fertility preference in Ghana.
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