Study On The Pyrolysis And Resource Recovery Technology Of Pressure Sensitive-adhesives Wastes

Due to the shortage of fossil oil resources, the research of oil-substitutes has been receiving more and more attentions. Pressure sensitive-adhesives wastes(PSAs), whose major components of PSAs are paper biomass, are produced during the process of stickers printing and the wastes from adhesive products used. The PSAs have been growing with the demand for adhesive increasing rapidly year by year. At present, less adhesive wastes have been recycled; moreover, the basic infrastructures and management system on PSAs in our country are not perfect yet. The problem of the treatment of PSAs is predictably more and more serious with the rapid development of adhesives in the foreseeable future. Therefore, it is necessary to carry out the exploration and research on the high efficient dispoal and recycling technology with high value of PSAs. In this paper, the resin adhesive wastes, widely used in our country, had been used as materials in the experiments, in order to study the reduction and recycling by pyrolysis in the low or medium temperatures. It is hoped that the study in this paper can provide an effective technical approach for the disposal and high value recovery of PSAs, moreover, gives a positive significance on the alleviating the current situation of the shortage of fossil oil resources in our country.In our study, the basic physicochemical poperties of PSAs have been study firstly in the aspects of compositions of raw material, proximate analysis, ultimate analysis and the ash compositions. The properties of weightloss of raw material and the components with the rising of temperature are studied by TG analysis. And the composions of volatiles from the thermal decompositions of raw materials are analyzed by TG-FTIR and Py-GC/MS. The kinetics parameters of the pyrolsis of PSAs materals and the components are calculated in order to emphatically discusses the synergetic effect on the promoting the weightloss during the process of pyrolysis. On this basis, the researches on PSAs pyrolysis in a fixed-bed reactor had been carried out for the study of the yields and the components of products, which could provides an important experimental conclusions in the diposal degree and the resource level of PSAs pyrolysis. Furthermore, the oil from PSAs pyrolysis has ‘three high(3H)' chacrateristics on the viscosity, acid number and oxygen content. Thus, the experiments of catalytic pyrolysis of PSAs with Ca O, Mg O, molecular sieve, PSAs char and combustion ash of char as catalysts are conducted for reducing of the viscosity, acid number and the oxygen content and the improvement in the quality of oil. The further investigations of copyrolysis of rice husk or branch biomass with PSAs were also carried out. The yields of copyrolysis and the compositions of the products are also studied for the purpose of the analysis of the synergetic effect on the changing the quantity and quality of oil during the copyrolysis. At last, the mass balance and energy balance were calculated to give a preliminary economic assessment of PSAs pyrolysis and provide the correlative basis data for the disposal and recovery of PSAs by pyrolysis.The conclusions could be drawn as follows:(1) Paper biomass is given priorigy to PSAs components, followed by the the plastic film, bottom paper protective film and binder. The results of proximate analysis showed that the volatile content is up to 80.43%, the fixed carbon content is 6.84%, and the ash content is 10.47%, which provides a good material foundation for reducing the content of PSAs by pyrolysis. The oxygen content in PSAs is 46.04%, which would give influences on the products, especially the quality of pyrolysis oil. The ash components of ash showed that the content of Ca O is 57.78%, followed by Si O2(20.81%) and Al2O3(13.37%). In addition, the content of Na2 O and Mg O also both have higher contents, which reach 2.63% and 1.24% respectively.(2) In the nitrogen atmosphere, the main weightloss temperature scale is between 300? and 550?. Heating rate has significant effect on the final weighloss rate. When the heating rate is 20?/min, the weightloss rate has a maximum content. The paper components are given priority to the weight loss process. Moreover, the weightloss temperature scales between the components of PSAs exists overlapping. The kinetics of pyrolysis of PSAs and the major components show that the apparent activation energy of PSAs are lower than that of the components, which demonstrates that the overlapping interaction of components during the pyrolysis process is beneficial to promote the process of PSAs pyrolysis. TG-FTIR analysis results show that volatiles from paper components pyrolysis contain carboxylic acid compounds, hydrocarbons, ketones compounds, CO2 and water. The volatile of adhesive pyrolysis is mainly for the carboxyl oxygen containing functional group and methyl or ethyl hydrocarbons. The volatile from plastic film and protection film of base paper pyrolysis are hydrocarbons. Py-GC/MS analysis results show that the compostions of valotiles at the low temperature, mainly from paper pyrolysis, contains acids, alcohols, aldehydes, ketones, furan and sugar and other products. The resin content rises with the rising of temperature. When the pyrolysis temperature is 450?, the content of resin gets the maximum content. Plastic film and bottom paper protecting film begin to be cracked at last, which form a large number of fatty hydrocarbon and aromatic compounds, especially the significant increase in production rate of benzene and its homologue. When the temperature higher than 550?, the product in the polycyclic aromatic hydrocarbons.(3) The results of fixed-bed experiments of PSAs pyrolysis show that it is obvious that the pyrolysis can reduce the content of PSAs effectively in the lower or medium pyrolysis temperatures. The organic components cracked quickly with the rising of temperature, which can be manifested by the conversion rate. The conversion rate, 77.30% at 400?, 85.85% at 500?, gets up to 90.73% as the temperatures is 700?. The products of PSAs pyrolysis at low and medium temperautes are given priorigy to the liquid products. Both the yield of liquid products and oil rise at lower temperatures, and get a maximum yield at a medium temperature. The yield of liquid product get a maximum yield at 550?, which is 55.69 wt.%. However, the oil yield get to maximum at 600?, which is 31.47%. The yield of char from PSAs pyrolysis decreases with the rising of temperature, however, the yield of gas increases. The density of pyrolysis oil from PSAs pyrolysis is between 0.81g/cm3 and 0.91g/cm3; the viscosity is between 6.66mm2/s and 15.17mm2/s. The viscosity of oil increases with the longer duration of stay, which is unfavorable for the storage and use of pyrolysis oil. The oxygen content in pyrolysis oil is between 18.68% and 22.57%, which leads to the growing of viscosity and the reducing of oil by the reactions of oxidation and polymerizaition during the storage. The main components in gas are CO2 and CO, followed by CH4 and H2, which lead to the low calorific value of gas. The calorific value of char is between 17.65MJ/kg and 13.09MJ/kg. The BET area of char is between 44.02m2/g and 127.26m2/g.(4) The results of the catalytic pyrolysis of PSAs show that alkaline earth metal, molecular sieve, char, and PSAs char combustion ash have important effect on the yields of PSAs pyrolysis and the quality of oil. Comparing with the effect of lkaline earth metal and molecular sieve, PSAs char can effectively reduce the viscosity, acid number and oxygen content, at the same time, PSAs char has lower effect on reducing the yield of pyrolysis liquid pyrolysis oil. Moreover, the PSAs char placed after the process of PSAs pyrolysis is better than that of physical mixing. The density, viscosity and oxygen in the oil from the pyrolysis with char placed separately are closed to those in biodiesel. The ash from the combustion of PSAs char has little effect on the viscosity of oil, however, obtains great effect on the acid number, oxygen content and the calorific value of oil. The GC-MS analysis results indicate that the content of carboxylic acids and alcohols compounds in the oil from the catalytic pyrolysis by char both decreases, meanwhile, the content of ester compounds increases. It is believed that the polyolefin plastic film and protective film of bottom paper might play the role of hydrogen donator, which promotes the conversion of carboxylic acid compounds into ester compounds. The alcohol compounds in the volatiles might also act as the role of hydrogen donator, which will converted into esters compounds on the suface of catalysts with carboxylic acid compounds. Furthermore, there exits significant differences of the dydroxyl groups contained in the char surface before and after the catalytic reacors, which may enhances the decarboxylation reactions, thereby improving the liphatic hydrocarbons and polycyclic aromatic dydrocarbons.(5) The experiment results of co-pyrolysis of PSAs and biomass shows that there exists synergetic effect on the yield of copyrolysis of PSAs and biomass at different blending ratios. When the ratio of PSAs/biomass is 3/1, the synergetic effect is most obvious, especially on promoting the yields of liquid products and pyrolysis oil. The copyrolysis of PSAs and biomass has little effect on the viscosity as the blending ratio is 3/1. Comparing with the blank experiment, in which the acid number is 49.20 mg KOH/g, the acid number of oil in the copyrolysis of PSAs and biomass could be reduced. When the blending ratio of PSAs/Rice husk is 3/1, the acid number is 47.95 mg KOH/g; when the blending ratio of PSAs/Branch is 3/1, the acid number is 39.38 mg KOH/g. Oxygen content of co-pyrolysis oil can be significantly reduced as the ratio of PSAs/biomass is 3/1. When the blending ratio of PSAs/Rice husk is 3/1, the oxygen content of oil can be reduced to 10.42%, the ratio of oxygen reduction is 53.81%. When the blending ratio of PSAs/Branch is 3/1, the ratio of oxygen is reduced to 14.70%, the ratio of oxygen reduction is 34.44%. Due to the GC-MS analysis of copyrolysis oil, it can be predicted that the synergetic effect might be maintained by the cracking of biomass, which adds the content of ketenes in the volatiles promoting the reactions of carboxylic acid compounds and ketenes. The reactions of carboxylic acid compounds and ketenes improve the content of esters in the copyrolysis oil.(6) The analysis of energy balance and preliminary economic assessment show that the PSAs pyrolysis technology has low power comsumption. The recycle ratio of energy is 0.67, which manifests that the recovery of energy from the PSAs pyrolysis is high. The energy recovered from the PSAs pyrolysis technology much higher than the comsumption, which indicates that pyrolysis is a promising technology for the diposal and recovery of PSAs.