The Technology Of Purifying Cooking Oil Fumes Over Rare Earth Loading Catalyst

The cooking oil fumes pollution has been becoming a serious problem, with the appearance of more and more big restaurants in cities of China. According to corresponding researches there are many noxious and harmful components in cooking oil fumes, some of which are carcinogens and may cause mutations. As a result, the exclusion of oil fumes affects the life of urban residents greatly, and complains of this issue account for 40% of the total on environment discontentment. So the government has enacted relevant laws, forcing the owner of restaurants to purify it in 2000.Though several methods on disposal technology of oil fumes have been developed at home and abroad, such as filtration process, electrostatic process and wet process, practical and effective technology is still needed. It shows that among various methods for purifying cooking oil fumes, the cost of purifying method changes as the purifying efficiency changing. In our country, we used to use the mechanism way to purifying cooking oil fumes of which the disadvantage is the fumes let out with out any chemical reaction so that it would pollute the air. Overseas, cooking oil fumes used to be purified by combustion or catalysis, although it is based on the low concentration of cooking oil fumes. In theory, the way suit our country is not mature. How to find out an effective and costless method is one the aim of the research.Catalysis is the best effective and economical method among the treatments of organic pollutes. A lot of researches prove that rare earth element is a good assistant to catalysis, and it can improve the catalysis of catalyst by mixing rare earth elements such as La, Ce, and transition metal. The principle of purifying cooking oil fumes by catalysis is that using catalyst have self-purifying function can translate oil droplet into CO2 and H2O at the cooking temperature through the cooking, and eliminate pollute and odor also.Due to the extreme complexity of cooking oil fumes compositions, about 200 kinds, the first crucial task for this research is to develop a suitable evaluation system for purification efficiency of catalysts. Though many trials, a scientific and accurate method was set up in our lab. First, compressed air flow going through the cooking oil was used to produce oil fumes and oil fumes with the same flow rate and similar composition to the real situation was obtained. Second, the method of absorbing oil fumes by the tube filled with CCl4 solvent was developed, which was practical and gained high absorbing efficiency. Third, IR method was used to measure the concentration of the solution.Because cooking oil fumes are viscous, it can not be reused for usual catalysis reaction tube. And usual catalysis reaction tube are large occupation of land, and not easy to mobile. For these questions, a new kind of catalysis reaction tube was designed, which can resistant high temperature and erosion, mobile, easy to be separation and washing, and reusable.Experimental table of catalysis purifying is established. On this table, orthogonal experiment and normal experiment are carried out. Through experiments, main factors influencing efficiency of purifying and the influencing degree are testified; therefore, some regularities of the catalysis purifying method are received.In the condition of 30% catalyst's loading, 800°C calcinations temperature, 300°C catalyst temperature and 10L/min gas flow, the Catalyst had the best effect on fume purification that could reach 88%. According to the results of analysis of variance and range, the factors which impact fume purification were ranked in strength order as followed: calcinations temperature, loading, flow, Catalyst temperature.The XRD, SEM, BET experiments were carried out to estimate the selected catalyzes'physical and chemical characters. And the results of physical and chemical character experiments not only testified the results of the compared experiments but also provided theoretic base of the catalyzes'improvement.At last,GC-MS experiment was carried out to detect the composition of cooking oil fumes before and after catalysis purifying experiment, which is the other measure for estimating the catalyst ability.