[Document Name] Specification [Title of Invention] LIQUID FOR ABSORBING AND COLLECTING CARBON DIOXIDE IN GAS, AND METHOD FOR COLLECTING CARBON DIOXIDE WITH USE OF SAME [Technical Field] [0001] The present invention relates to a liquid for absorbing and recovering carbon dioxide contained in a gas, and a method 10 for efficiently absorbing and recovering carbon dioxide in a gas, the method using the liquid. [Background Art] [0002] 15 In recent years, climate change and natural disasters presumably caused by global warming have had a serious influence on agricultural production, living conditions, energy consumption, etc. Global warming is believed to be due to an increase in greenhouse gases, such as carbon dioxide, methane, nitrous oxide, 20 and chlorofluorocarbons (CFCs), in the atmosphere, in association vii th an increase in human activity. The main gas among the greenhouse gases is atmospheric carbon dioxide, and there is thus a worldvlide need for a measure to reduce carbon dioxide emissions into the atmosphere. 25 [0003] Examples of sources of carbon dioxide include thermal pOiver plants using coal·, heavy oil, natural gas, or the like as a fuel; ironworks blast furnaces where iron oxide is reduced with coke; ironworks converters where carbon in pig iron is combusted 30 to produce st.eel; factory boilers; cement plant kilns; and transportation equipment using gasoline, heavy oil, light oil, or the like as a fuel, such as automobiles, ships, and aircrafts. Except for transportation equipment, these sources of carbon dioxide are fixed facilities, which are easily adapted to 35 implement measures for reducing carbon dioxide emissions into the atmosphere. [0004] -2- Several methods for separating and recovering carbon dioxide from gases exhausted from the above-mentioned sources are 5 hitherto known. [0005] For example, a method for absorbing carbon dioxide by bringing an aqueous solution of an alkanolamine into contact with a carbon dioxide-containing gas in an absorption tower is known. 10 Examples of known alkanolamines include monoethanolamine (MEA) , diethanolamine (DEA), triethanolamine (TEA), methyl diethanolamine (MDEA), diisopropanolamine (DIPA), diglycolamine (DGA), and the like. Typically, MEA is often used. 15 [ 0006] In general, alkanolamines have high solubility in 1·mter, and the alkanolamine concentration is preferably higher to more efficiently separate and recover carbon dioxide. However, the rate at which carbon dioxide is recovered decreases as the a1kanolamine concentration increases. Thus, the development of a 20 liquid, for absorbing carbon dioxide, that achieves higher reaction efficiency has not been attained. [0007] To recover carbon dioxide from a liquid in which the carbon dioxide is absorbed, the liquid is heated to, for example, 25 120°C to separate the carbon dioxide from the liquid containing the absorbed carbon dioxide. However, when the heat of reaction between the carbon dioxide and the alkanolamine is high, a large amount of energy is required to recover the carbon dioxide. For example, when MEA is used, the heat of reaction with one mole of 30 carbon~dioxide is as high as 80 kJ (80 kJ/mol C02), and to separate and recover carbon dioxide in an electric power plant by using MEA, energy that corresponds to about 20% of the generated electric power is required. [0008] 35 From the viev~oint of carbon dioxide emissions into the -3- atmosphere, as well as energy-saving and resource-saving, this additional energy consumption is a major problem in the practical use for separation and recovery of carbon dioxide. There is thus a need for a carbon dioxide-absorbing liquid for absorbing and 5 recovering carbon dioxide with lower energy consumption, i.e., with high energy efficiency, and a method therefor. [0009] Various studies have been conducted to address the above problems. Patent Literature 1 discloses a method for 10 removing carbon dioxide from a combustion exhaust gas, the method comprising bringing an aqueous solution of a so-called hindered amine, which is an amine compound having a steric hindrance of alkyl groups or the like around the amine group, into contact with a combustion exhaust gas at atmospheric pressure to absorb 15 carbon dioxide into the aqueous solution. Patent Literature 1 discloses 2-methylaminoethanol (•lhich hereafter may be referred to as MAE) and 2-ethylaminoethanol (which hereafter may be referred to as EAE) as specific examples of hindered amines. In the Examples of Patent Literature 1, an aqueous solution 20 containing 30 l·lt% of MAE or EAE ~