Synthesis Gas Conversion to Aliphatic Alcohols: Study of MoS2 catalytic systems

The recent energy debate and demand for renewable fuels has intensified research activities for conversion of biomass derived feedstocks to fuels and fuel additives. Synthesis of ethanol and higher aliphatic alcohols from syngas (CO + H2) is therefore receiving renewed interest. An important objective of this thesis was to develop commercially competitive catalysts and understand the fundamental issues affecting their performance. Molybdenum Sulfide (MoS2) class of catalysts were synthesized by sulfidation of ammonium thiomolybate and acetate salts of co-promoters. Several catalyst formulations were prepared by calcination, followed by doping with alkali promoters. Solid state modifications were made in some cases to dilute the active MoS2 material in supported catalysts. By modifying synthesis procedures, homogeneous and narrow size distribution of the sulfide material was obtained. Size control 2 agglomerates by a novel chelation synthesis technique, which was particularly useful in enhancing alcohol yields. The catalyst performance was studied in a fixed bed rector, operating in a range of 280-350oC, 69-92 bar and typical gas space velocities of 3000-10000 L/g.cat/hr. Analytical equipment with the capability to perform online gas phase analysis of oxygenates along with permanent gases was setup. This led to the quantitative determination of reactants/products concentrations in a time-on-stream run and detection of oscillations in concentration profiles of oxygenates. Such an oscillatory behavior has not been reported before and it could be important for safe operation and understanding the scale up parameters of the process. Alcohol active catalysts were thoroughly tested for steady state activity and evaluated for parametric effects on conversion and selectivity. Depending upon the composition, a catalyst showed varying sensitivity to operating conditions. Temperature, space velocity and CO:H2 ratio in the syngas possessed the greatest capability in altering the product portfolio and overall reaction rates. Use of co-promoters like Cu, led to increased alcohol selectivity of >85%, whereas promoters like Rh significantly improved the yield of alcohols (alcohol yields > 500 g/kg.cat/hr). Such high yields and selectivities are indicative of a major advancement over the existing MoS85%, whereas promoters like Rh significantly improved the yield of alcohols (alcohol yields > 500 g/kg.cat/hr). Such high yields and selectivities are indicative of a major advancement over the existing MoS 500 g/kg.cat/hr). Such high yields and selectivities are indicative of a major advancement over the existing MoS2 based catalyst systems. By changing the support type and modifying support basicity, selectivity for alcohols as well as overall alcohol yield could be improved by 3 times at temperatures > 300 300oC. Modification of aluminosilicate supports by interchanging framework cations has not been reported for higher alcohol synthesis and offers a very simple technique for enhancing performance of supported catalysts. Use of zeolites as supports offers increased C2+/C1 alcohol ratios from nominal value of 2 to 4. Active catalysts were characterized by SEM, TEM, EDS and XRD, which revealed that the final catalyst morphology greatly affects the alcohol synthesis performance of the catalyst

Modelling an integrated impact of fire, explosion and combustion products during transitional events caused by an accidental release of LNG

In a complex processing facility, there is likelihood of occurrence of cascading scenarios, i.e. hydrocarbon release, fire, explosion and dispersion of combustion products. The consequence of such scenarios, when combined, can be more severe than their individual impact. Hence, actual impact can be only representedby integration of above mentioned events. A novel methodology is proposed to model an evolving accident scenario during an incidental release of LNG in a complex processing facility. The methodology is applied to a case study considering transitional scenarios namely spill, pool formation and evaporation of LNG, dispersion of natural gas, and the consequent fire, explosion and dispersion of combustion products using Computational Fluid Dynamics (CFD). Probit functions are employed to analyze individual impacts and a ranking method is used to combine various impacts to identify risk during the transitional events.The results confirmed that in a large and complex facility, an LNG fire can transit to a vapor cloud explosion ifthe necessary conditions are met, i.e.the flammable range, ignition source with enough energy and congestion/confinement level. Therefore, the integrated consequences are more severe than those associated with the individual ones, and need to be properly assessed. This study would provide an insight for an effective analysis of potential consequences of an LNG spill in any LNG processing facility and it can be useful for the safety measured design of process facilities

Review and analysis of fire and explosion accidents in maritime transportation

The globally expanding shipping industry has several hazards such as collision, capsizing, foundering, grounding, stranding, fire, and explosion. Accidents are often caused by more than one contributing factor through complex interaction. It is crucial to identify root causes and their interactions to prevent and understand such accidents. This study presents a detailed review and analysis of fire and explosion accidents that occurred in the maritimetransportation industry during 1990–2015. The underlying causes of fire and explosion accidents are identified and analysed. This study also reviewed potential preventative measures to prevent such accidents. Additionally, this study compares properties of alternative fuels and analyses their effectiveness in mitigating fire and explosionhazards. It is observed that Cryogenic Natural Gas (CrNG), Liquefied Natural Gas (LNG) and methanol have properties more suitable than traditional fuels in mitigating fire risk and appropriate management of their hazards could make them a safer option to traditional fuels. However, for commercial use at this stage, there exist several uncertainties due to inadequate studies, and technological immaturity. This study provides an insight into fire and explosion accident causation and prevention, including the prospect of using alternative fuels for mitigating fire and explosion risks in maritime transportation

Acute Administration of Caffeine: The Effect on Motor Coordination, Higher Brain Cognitive Functions, and the Social Behavior of BLC57 Mice

Excessive caffeine consumption causes adverse health effects. The effects of moderate and high doses of caffeine consumption on the motor coordination, cognitive brain functions, and the social behavior in mice were studied. Animals were divided into three groups: control group, moderate dose group (Ac MD), and high dose group (Ac HD). The animals were tested after 7 days of caffeine administration. A rotarod test for motor coordination showed that the mice of the moderate dose group could stay on the rotating rod longer before falling in comparison to the control group and the high dose group. A water maze test for learning and memory showed better performance of mice receiving the moderate dose of caffeine compared to the other groups. Animals that were administered moderate as well as high doses of caffeine showed no sociability and no preference for social novelty in the three-chamber test used to test social behavior. In an elevated plus maze test, control animals showed no anxiety-like behavior while mice from both of the groups administered with caffeine showed anxiety-like behaviors. Our data conclude that the effects of caffeine on higher brain functions depend on the administration dose. When caffeine was given in moderate doses, it resulted in enhancement of memory and motor coordination functions. However, high doses caused defects in memory and learning. The social behavior of the mice, as determined by the level of anxiety and sociability, was affected negatively by moderate as well as high dose caffeine administration

Staying ahead of the curve: Navigating changes and maintaining gains in patient safety culture - a mixed-methods study

Objectives This study examines how the results of the Hospital Survey on Patient Safety Culture changed between 2012 and 2019 and identifies organisational factors affecting these changes.Design The study combined the use of quantitative surveys of staff and qualitative interviews with hospital leadership. Secondary data analysis was performed for previous surveys.Setting This study was conducted in a tertiary care teaching multisite hospital in Riyadh, Saudi Arabia.Participants One thousand hospital staff participated in the survey. Thirty-one executive board members and directors and four focus groups of frontliners were qualitatively interviewed.Primary and secondary outcome measures Twelve safety culture dimensions were assessed to study the patient safety culture as perceived by the healthcare professionals. An additional semi-structured interview was conducted to identify organisational factors, changes, and barriers affecting the patient safety culture. Furthermore, suggestions to improve patient safety were proposed.Results Comparing the results revealed a general positive trend in scores from 2012 to 2019. The areas of strength included teamwork within and across units, organisational learning, managerial support, overall perception of safety and feedback and communication about error. Non-punitive response to error, staffing and communication and openness consistently remain the lowest-scoring composites. Interview results revealed that organisational changes may have influenced the answers of the participants on some survey composites.Conclusions Patient safety is a moving target with areas for improvement that are continuously identified. Effective quality improvement initiatives can lead to visible changes in the patient safety culture in a hospital, and consistent leadership commitment and support can maintain these improvements