发达国家应帮助非洲应对气候变化

前不久,第七届可持续发展世界论坛布基纳法索首都瓦加杜古落下帷幕。与会代表发表声明,一致呼吁发达国家承诺加大减少温室气体排放力度,帮助非洲应对气候变化。声明指出,非洲大陆本身并不能解决所有与气候变化有关的问题,因此要求全球的合作伙伴积极维护《京都议定书》等协议的成果。本次以“气候变化:对可持续发展有什么样的机遇”为主题的论坛由布基纳法索政府、联合国以及非洲联盟联合举办。布基纳法索总统孔波雷和刚果(布)总统萨苏、中非总统博齐泽和科特迪瓦总理索罗等多名非洲国家领导人与会。非洲联盟委员会主席让.平表示,与其它地区相比,非洲在应对气候变化方面的能力最弱,并且还不具备应对由此导致的环境与生态恶化的所需手段。因此,非洲国家决定在应对气候变化方面采取共同立场,要求发达国家承诺加大减少温室气体排放力度,并将于今年12月在丹麦哥本哈根举行的联合国气候变化大会上用同一个声音说话。长期以来,发展中国家、最不发达国家和小岛国排放的温室气体最少,却是气候变化的最大受害者。以非洲大陆为例,非洲国家所排放的温室气体仅占世界的4%,但却是全球气候变暖的主要受害者,其应对气候变化的能力也最弱。资料显示,从现在到2020年,预计全球变暖将造成非洲...     

全球气候变暖中的大气化学问题

介绍全球气候变暖中的大气化学问题。讨论臭氧层破坏的化学机理,从化学结构角度分析温室气体对温室效应的影响,并给出解决气候变暖的应对措施。     

全球气候变暖问题的化学教学思考*

以学生的课堂质疑为背景,从温室效应和全球气候变暖的概念区别、全球气候变暖成因的证据、温室气体种类的界定3个层面,论述了由于具有历史局限性的证据和缺少对科学态度的真正理解,导致全球气候变暖问题出现了教学和认识上的误区。     

温室气体及其全球增暖潜势

本文介绍全球气候变暖和温室效应增强的严重事实；本世纪９０年代提出的“气候变化的辐射强迫”概念；不同温室气体的源和汇及全球增暖潜势     

二氧化碳的捕集、存储及转化

2009年哥本哈根全球气候大会之后,如何减排导致全球气候变暖的温室气体之一的CO₂,并能将CO₂转化成有用化工产品成为当前全球研究的热点.本文总结了至今在CO₂捕集、存储和转化方面的进展工作.另外,结合各种CO₂利用技术的原理和特点,总结出这些技术的优势与不足,对CO₂的利用前景进行了展望.     

认识“碳足迹”倡导低碳生活

温室效应及温室气体的排放是全球气候变暖的重要原因,“碳足迹”是近年来国际环保组织及研究者为了形象而准确地衡量温室气体排放对气候以及人类生活的影响提出的新概念,用于测量人类活动中产生的全部温室气体,并以二氧化碳作为等价物,以吨（或千克）为单位计算温室气体的量。这一概念促使人们认识到,在现代生活中每一个人都在这个世界上留下了“碳足迹”,减少“碳足迹”,倡导低碳生活人人可为,有利于唤醒人们的环境意识与责任。论文介绍了“碳足迹”的含义及计算方法,讨论了个人生活与“碳足迹”的关系,从“碳中和”、做出承诺、节能减排、支持新能源的开发与应用等方面提出减少“碳足迹”的建议。     

大气微量气体的辐射强迫与温室气候效应

本文使用改进的辐射对流模式,计算了大气微量气体的辐射强迫与温室气候效应,给出了辐射强迫与气体含量变化的关系式。结果发现:(1)大气温室气体的辐射强迫与温室气候效应受到不同气体吸收带重迭的重大影响;(2)大气CO_2以外的其它微量气体(例如CH_4,N_2O和CFCs等)浓度的增加对未来的气候变暖可能起重要作用;(3)目前据认为对大气O_3层有破坏作用的含氯氟烃类物质(如CFC11,CFC12,CFC113,CFC114,CFC115)的代用品(如HCFC124,HFC125等),其O_3消耗潜能(ODP)虽小,但依然具有较强的温室气候效应;(4)地气系统的各种反馈过程对地面温度的变化具有重大影响。     

二氧化碳与环氧化合物反应均相催化剂的研究进展

现在全世界每年产生二氧化碳的量已超过百亿吨,预计到2010年全球二氧化碳的排放量将是278亿吨．二氧化碳是一种温室气体,它在大气中的含量不断增加会导致全球变暖,造成全球性气候异常,给生态环境带来严重影响,引发频繁的自然灾害．因此,如何控制二氧化碳的排放已经引起世界范围的广泛关注．2007年12月在印度尼西亚巴厘岛召开的联合国巴厘国际气候会议重点讨论了二氧化碳的排放问题,目前世界各国均投入大量人力物力进行二氧化碳的治理,如发达国家研发将二氧化碳收集并深埋地下,在治理的同时也限制企业二氧化碳排放量．     

温室气体排放提前达到危险极限

澳大利亚顶尖气候专家说，全球强劲的经济增长势头加速了空气中温室气体水平的升高，目前该水平已经达到了科学家原先预测再过十年才会出现的危险极限。     

无金属参与的CO_2催化转化的研究进展

CO2既是导致全球变暖的主要温室气体,又是来源丰富廉价易得的可再生C1资源,因此CO2的资源化利用是绿色化学的重要研究方向之一.本文作者分别从无金属参与的CO2催化转化制备五元环状碳酸酯、噁唑啉酮以及CO2还原等几个方面对其催化转化进行综述,并对CO2有机催化转化进行了展望.     

Fluorocarbons in the global environment: a review of the important interactions with atmospheric chemistry and physics

Fluorocarbon impact on ozone depletion is reviewed together with the efficacy of the Montreal Protocol in acting to correct the imbalance between stratospheric ozone production and destruction. The Protocol is also helping to reduce global warming: CFCs are shown to be currently the largest fluorocarbon contributors to climate change. Relative contributions to climate change from CFCs and their HFC substitutes are discussed, together with the consequences of control of minor greenhouse gases on an environmental impact which is dominated by carbon dioxide emissions. Both the potencies of the materials for environmental change and their concentrations in the atmosphere are important and are considered here.Trifluoroacetic acid, a minor product of atmospheric decomposition of some HCFCs and HFCs and of the pyrolysis of fluoropolymers, has been shown to be uniformly distributed in seawater to a depth of over 4000 m and so is natural, although the actual source has yet to be identified.The Montreal Protocol is only one example of action to reduce undesirable impact from fluorocarbons. Other, less universal, actions include abatement of fluoroform greenhouse gas emissions from HCFC manufacturing, process changes to eliminate trifluoromethylsulfur pentafluoride emissions from electrochemical fluorination and ceasing manufacture of perfluorooctanyl sulfonate compounds due to their persistence in human tissue.     

Evaluation of carbon dioxide equivalent values for greenhouse gases: CEWN as a new indicator replacing GWP

A new indicator, the CEWN (Carbon Dioxide Equivalent Warming Number), is proposed as an alternative to the GWP (Global Warming Potential). CEWN is a metric where the global warming by the emission of gases is compared unifying the removal rate of each gas from the atmosphere, using carbon dioxide as a reference. To comply with the basket system of the Kyoto Protocol, GWP is used with a 100-year time horizon, making it unsatisfactory for the evaluation of long-lived compounds. As the removal rate from the atmosphere depends on the lifetime, the CEWN presents a fair assessment of the relative global warming.     

Confined Ni-In intermetallic alloy nanocatalyst with excellent coking resistance for methane dry reforming

Carbon dioxide and methane are two main greenhouse gases which are contributed to serious global warming.Fortunately,dry reforming of methane(DRM),a very important reaction developed decades ago,can convert these two major greenhouse gases into value-added syngas or hydrogen.The main problem retarding its industrialization is the seriously coking formation upon the nickel-based catalysts.Herein,a series of confined indium-nickel(In-Ni)intermetallic alloy nanocatalysts(In_xNi@SiO₂)have been prepared and displayed superior coking resistance for DRM reaction.The sample containing 0.5 wt.%of In loading(In_0.5Ni@SiO₂)shows the best balance of carbon deposition resistance and DRM reactivity even after 430 h long term stability test.The boosted carbon resistance can be ascribed to the confinement of core–shell structure and to the transfer of electrons from Indium to Nickel in In-Ni intermetallic alloys due to the smaller electronegativity of In.Both the silica shell and the increase of electron cloud density on metallic Ni can weaken the ability of Ni to activate C–H bond and decrease the deep cracking process of methane.The reaction over the confined InNi intermetallic alloy nanocatalyst was conformed to the Langmuir-Hinshelwood(L-H)mechanism revealed by in situ diffuse reflectance infrared Fourier transform spectroscopy(in-situ DRIFTS).This work provides a guidance to design high performance coking resistance catalysts for methane dry reforming to efficiently utilize these two main greenhouse gases.     

Kinetics of chemical absorption of carbon dioxide into aqueous calcium acetate solution

Increasing energy demand in the world leads to more electricity generation mainly at fossil fuel power plants. Greenhouse gases are thus produced and mostly emitted to the atmosphere directly, resulting in global warming and climate change. Carbon dioxide is believed to be a main pollutant among greenhouse gases responsible from global warming. Conventional systems using mostly amine solutions to capture carbon dioxide at the source have some disadvantages, and alternatives are constantly being searched. In this work, a benign system of aqueous calcium acetate solution was investigated for this purpose. Calcium acetate is easy to produce, relatively cheap, environmentally friendly, nonhazardous, and noncorrosive. These properties make it a great alternative for use in capturing carbon dioxide. This absorption process is accompanied by chemical reaction. Therefore, the reaction kinetics needs to be investigated before its use in absorbers. A stirred cell reactor was used in the experiments using aqueous calcium acetate solution of different concentrations (2-20% w/w) and different carbon dioxide concentrations in gas mixtures (4.5-100% v/v dry carbon dioxide) at temperatures ranging from 286 to 352 K. The Gibbs free energy change for the overall reaction between carbon dioxide and aqueous calcium acetate solution was found to be –2.75 kJ/mol that shows the reaction is exergonic and occurs spontaneously. It was also found out that the reaction is pseudo–first order with respect to carbon dioxide which was also proven by calculating the Hatta number. Activation energy and Arrhenius (frequency) constant were also determined experimentally.     

Utilization of Deep Eutectic Solvents to Reduce the Release of Hazardous Gases to the Atmosphere: A Critical Review

The release of certain gases to the atmosphere is controlled in many countries owing to their negative impact on the environment and human health. These gases include carbon dioxide (CO₂), sulfur oxides (SOx), nitrogen oxides (NOx), hydrogen sulfide (H₂S) and ammonia (NH₃). Considering the major contribution of greenhouse gases to global warming and climate change, mitigation of these gases is one of the world’s primary challenges. Nevertheless, the commercial processes used to capture these gases suffer from several drawbacks, including the use of volatile solvents, generation of hazardous byproducts, and high-energy demand. Research in green chemistry has resulted in the synthesis of potentially green solvents that are non-toxic, efficient, and environmentally friendly. Deep eutectic solvents (DESs) are novel solvents that upon wise choice of their constituents can be green and tunable with high biocompatibility, high degradability, and low cost. Consequently, the capture of toxic gases by DESs is promising and environmentally friendly and has attracted much attention during the last decade. Here, we review recent results on capture of these gases using different types of DESs. The effect of different parameters, such as chemical structure, molar ratio, temperature, and pressure, on capture efficiency is discussed.     

Recent Advances on Metal-Organic Frameworks in the Conversion of Carbon Dioxide

With the development of modern industry,global warming is becoming a challenging issue due to the emissions of large quantities of greenhouse gases,mainly carbon dioxide(CO₂).The conversion of CO₂to useful compounds is considered as an effective and economic way to solve such a climate problem.Metal-organic frameworks(MOFs)are an emerging class of porous crystalline materials that have shown great potential in the conversion of CO₂.The advantages of MOFs in CO 2 conversion lie in their high surface areas,adjustable pore size,and high porosity.More importantly,desirable functional sites can be easily designed and precisely installed to the pore wall of target MOFs by pre-assembly and/or post-synthetic modification(PSM)ways.This review summarizes the recent advances in constructing MOF catalysts for the application in CO₂conversion.We believe that the design and synthesis of MOF catalysts for CO₂conversion can be a promising way to solve the“greenhouse effect”.     

Thermal analyses of home-made zeolite by DSC and TG

Volatile organic compounds (VOCs) and greenhouse gases are the main factors involved in pollution control and global warming. Various treatment methods involving incineration, adsorption, etc., have been employed to reduce VOCs and greenhouse gases concentration in the operating environment and atmosphere. Activated carbon, zeolite, silica gel, and alumina have been broadly used to adsorb pollutants in various industrial applications. Based on the promising effect of adsorption, we analyzed and identified the thermal phenomena of home-made zeolite using various instruments. The endothermic reaction under 100?°C of home-made zeolite was identified as steam adsorption, which is an important discovery. The optimal adsorption temperatures of home-made zeolite have been determined at 200?C550?°C.     

Mechanisms of Carbon Sequestration in Highly Organic Ecosystems – Importance of Chemical Ecology

Organic matter decomposition plays a major role in the cycling of carbon (C) and nutrients in terrestrial ecosystems across the globe. Climate change accelerates the decomposition rate to potentially increase the release of greenhouse gases and further enhance global warming in the future. However, fractions of organic matter vary in turnover times and parts are stabilized in soils for longer time periods (C sequestration). Overall, a better understanding of the mechanisms underlying C sequestration is needed for the development of effective mitigation policies to reduce land-based production of greenhouse gases. Known mechanisms of C sequestration include the recalcitrance of C input, interactions with soil minerals, aggregate formation, as well as its regulation via abiotic factors. In this Minireview, we discuss the mechanisms behind C sequestration including the recently emerging significance of biochemical interactions between organic matter inputs that lead to C stabilization.