다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Foreword 1. Prosperity Lost 2. The Age of Irresponsibility 3. Redefining Prosperity 4. The Dilemma of Growth 5. The Myth of Decoupling 6. The 'Iron Cage' of Consumerism 7. Keynesianism and the 'Green New Deal' 8. Ecological Macro-Economics 9. Flourishing - within Limits 10. Governance for Prosperity 11. The Transition to a Sustainable Economy 12. A Lasting Prosperity Appendices References Endnotes

Prosperity without growth : economics for a finite planet

Biodiesel is produced by the transesterification of oil triglycerides with methanol or ethanol, in the presence of a homogeneous or heterogeneous catalyst. This study aims to report the results of the transesterification of sunflower oil with methanol to produce biodiesel using CaO nanoparticles supported on NaX zeolite as catalyst. The effect of the CaO nanoparticles concentration on the NaX zeolite surface was studied in the range of 5−25 wt %. The transesterification reaction was carried out at reflux temperature of methanol, atmospheric pressure, a reaction time of 6 h, and with a 6:1 molar ratio of methanol to sunflower oil. Catalyst characterization was carried out by X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. It was concluded that methyl esters content is highly influenced by basicity and that the best catalyst was the one holding 16 wt % CaO nanoparticles. The produced biodiesel was 93.5% methyl esters and was found to fulfill the specifications of Europ...

Preparation and Characterization of CaO Nanoparticles/NaX Zeolite Catalysts for the Transesterification of Sunflower Oil

The world is confronted with the twin crises of fossil fuel depletion and environmental degradation. The indiscriminate extraction and consumption of fossil fuels have led to a reduction in petroleum reserves. Petroleum based fuels are obtained from limited reserves. These finite reserves are highly concentrated in certain region of the world. Therefore, those countries not having these resources are facing a foreign exchange crisis, mainly due to the import of crude petroleum oil. Hence it is necessary to look for alternative fuels, which can be produced from materials available within the country. Although vegetative oils can be fuel for diesel engines, but their high viscosities, low volatilities and poor cold flow properties have led to the investigation of its various derivatives. Among the different possible sources, fatty acid methyl esters, known as Biodiesel fuel derived from triglycerides (vegetable oil and animal fates) by transesterification with methanol, present the promising alternative substitute to diesel fuels and have received the most attention now a day. The main advantages of using Biodiesel are its renewability, better quality exhaust gas emission, its biodegradability and the organic carbon present in it is photosynthetic in origin. It does not contribute to a rise in the level of carbon dioxide in the atmosphere and consequently to the green house effect. This paper reviews the source of production and characterization of vegetable oils and their methyl ester as the substitute of the petroleum fuel and future possibilities of Biodiesel production.

Biodiesel production through the use of different sources and characterization of oils and their esters as the substitute of diesel: A review

As in Chapter 10, examples of the use of process intensification outside the chemicals sector will aid technology transfer among those considering PI as a technology in any industry, and it is also believed that this will encourage innovation in areas where energy efficiency and the use of renewable energies are becoming increasingly important, such as absorption and adsorption cooling/air conditioning, micro-power generation and the plethora of electronics-based equipment in commerce and the home.

Another point worth making here, illustrated later in the chapter, is the time between concept and practical application of some intensified units – although the area of application may be one in which progress is seen to be made very rapidly by consumers. The Rotex (latterly Rotartica) absorption heat pump/chiller is a case in point and is an object lesson in patience – and, like the spinning disc reactor company Protensive, has subsequently succumbed to market forces beyond its control. One only needs to look to China to see exploitation of PI on a large scale, however.

The chapter concludes with our third Key Table, summarising PI applications.

Application Areas – the Built Environment, Electronics, and the Home

A B S T R A C T Biofuel, a renewable energy is mainly produced by transesterification of fatty acids either in presence of enzyme or catalysts The transesterification relies on the use of either strong base or strong acid homogeneous catalysts for effective performance; but, homogeneous catalysts are associated with a variety of technical hurdles that limit their use for biodiesel production Although there have been recent developments in heterogeneous catalysts for biodiesel production via transesterification; the separation of methyl ester (FAMEs) from crude glycerol and alcohol recovery are still major hindrances A possible alternative could be the use of solid acid catalysts in thermocatalytic cracking of triglycerides Sulphated zirconia catalyst was evaluated for thermocatalytic cracking of triglycerides at a relatively low temperature (270 o C) and atmospheric pressure The catalyst was found to be active toward cracking vegetable oils to methyl esters The catalyst at this temperature exhibited different selectivity towards formation of saturated and unsaturated methyl esters The catalyst yield of methyl esters under these conditions was 58% while 80% of the product being unsaturated This opens up the possibility of controlling the degree of saturation of the methyl ester product by catalyst choice, to produce more or less saturated fuels for different markets The range of products from gases to middle distillates and the unique selectivity for saturated and unsaturated esters may be a significant process advantage of this form of catalytic cracking An important long chain unsaturated alcohol (1Heptatriacotanol) was also identified The unsaturated alcohol is known as an industrial chemical

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Harnessing alternative technology for the sustainability of biodiesel production.

A wide range of unit operations are capable of intensification. In this chapter some of the more important intensification techniques are briefly discussed, in order to prepare the reader for the more detailed treatment provided in subsequent chapters.

Where appropriate, developments taking place after the writing of the first edition are included. It is particularly noticeable that there has been continuing and increasing activity in particular in the use of electric fields of all types, and in further scale reductions (micro- and now nano-scales).

The Mechanisms Involved in Process Intensification

• Continuous air flotation was used to harvest microalgae for transesterification. • KOH-catalysed in situ transesterification used to convert biomass into biodiesel. • Transesterification was not adversely affected by moisture of up to 80% in algae. • A 97% yield of biodiesel (FAME) was obtained in 10 minutes. • Energy savings were achieved by in situ transesterification of algae feedstock. Microalgae are important biodiesel feedstocks because of their high lipid content and low land requirement for cultivation. One method of harvesting and concentrating algal biomass is by means of a foam column using surfactant CTAB as a collector and foaming agent, however, the downstream treatments for the “foamate” produced have not yet been investigated. Here, the freshwater microalgae strain, Chlorella vulgaris , was harvested by a continuous dispersed air flotation column and the foamate obtained was used as the feedstock for conversion to biodiesel via in situ reactive extraction using KOH as the catalyst. The process variables were methanol: oil molar ratio (100:1 to 1000:1), reaction temperature (40–60°C) and reaction time (5–10 min). The maximum biodiesel yield from the foamate produced of 97% from C. vulgaris microalgae was accomplished at a molar ratio (methanol to oil) of 1000:1, a 60°C temperature of reaction and a 10 min time of reaction. Longer reaction times resulted in reduced fatty acid methyl ester (FAME) yield due to saponification, converting the FAME to soap. High FAME yields were obtained despite the presence of significant quantities of free fatty acids (6% lipid) in the C. vulgaris biomass. The method also exhibited greater tolerance to water than that observed in conventional transesterification conditions. At a methanol: oil molar ratio of 1000:1, the method was not adversely affected by the presence of up to 80% level of moisture in the microalgae. Hence, a viable, FFA-tolerant, water-tolerant process has been demonstrated for direct conversion of microalgae foamate to biodiesel, at mild conditions (60°C and below) in a short residence time (10 min). 

Adam Harvey

Papers

Application Areas – the Built Environment, Electronics, and the Home

Harnessing alternative technology for the sustainability of biodiesel production.

The Mechanisms Involved in Process Intensification

Direct and rapid production of biodiesel from algae foamate using a homogeneous base catalyst as part of an intensified process

Intensification of Algal Biodiesel by in situ transesterification