Preparation of PE wax by pyrolysis of LLDPE waste plastic in a pressure reactor under low temperature

doi:10.11949/0438-1157.20190619

Abstract

Abstract:

The thermal pyrolysis of liner low density polyethylene (LLDPE) has been carried out in a closed pressure reactor. The effects of pyrolysis temperature, residence time and reactor pressure on the yield, molecular weight and melting point of the products were investigated. The characterization of the products has been carried out using Fourier transform infrared (FTIR) spectroscopy. The results indicate that the PE wax obtained under the conditions of residence time of 15—60 min and pyrolysis temperature of ~260℃ exhibited better performance, with the melting point above 100℃ and the molecular weight of between 1400 and 4700. The FTIR show that the main components are linear alkanes and olefins. According to the kinetic analysis, since the closed reaction system increased the reaction pressure, the pyrolysis temperature and activation energy were reduced, the LLDPE cracking reaction was promoted, and the generation of gas molecule was suppressed, which facilitated the formation of PE wax.

Key words: linear low-density polyethylene, pressure reactor, pyrolysis, PE wax, kinetics

摘要：

以废旧线性低密度聚乙烯（LLDPE）为原料，采用压力反应釜在封闭条件下通过热裂解方法制备聚乙烯蜡（PE蜡），研究了裂解时间、温度和压力对产物的产率、分子量和滴熔点的影响，并通过红外光谱对产物的官能团进行了分析。实验结果表明，在裂解时间为15~60 min，裂解温度约为260℃的条件下，LLDPE裂解所得到的PE蜡性能较佳，其主要成分为直链烷烃和烯烃，滴熔点大于100℃，黏均分子量处于1400~4700；由动力学分析可知，由于封闭反应体系增加了反应压力，降低了裂解温度和活化能，促进了LLDPE裂解反应进行，同时抑制了气体分子的产生，有利于获得PE蜡。

关键词: 线性低密度聚乙烯, 压力反应釜, 热解, PE蜡, 反应动力学

CLC Number:

TQ 031.3

Chuanqiang LI, Siyuan LIU, Dongsheng WANG, Shubin LIU, Xuxu ZHENG, Xiaoya YUAN. Preparation of PE wax by pyrolysis of LLDPE waste plastic in a pressure reactor under low temperature[J]. CIESC Journal, 2019, 70(12): 4856-4863.

李传强, 刘思媛, 王东升, 刘书彬, 郑旭煦, 袁小亚. 压力反应釜中低温热裂解废旧LLDPE塑料制备PE蜡[J]. 化工学报, 2019, 70(12): 4856-4863.

Figures/Tables 11

Fig.1 Linear low-density polyethylene(LLDPE)(a) and pressure reactor(b)

Fig.2 TG-DSC curves of LLDPE (N2, the heating rate is 10℃/min)

Fig.3 Appearance topography of products under different pyrolysis temperatures (the pyrolysis time is 30 min)

Fig.4 Yields of solids, liquids and gases under different pyrolysis temperatures at reaction time of 30 min

Table 1 Drop melting point and viscosity-average molecular weight of products

裂解温度/℃	滴熔点/℃	黏均分子量
200	124	10286
220	120	8417
240	118	7861
260	110	2489
280	108	1027
300	101	846

Fig.5 Yields of solid product obtained from pyrolysis of LLDPE under different pyrolysis time

Table 2 Pressure of reactor under different pyrolysis conditions

温度/℃	压力/MPa
温度/℃	15 min	30 min	45 min	60 min
240	0.2	1.0	1.2	1.5
260	0.4	1.6	2.6	3.2
280	0.6	2.0	3.7	4

Table 3 Drop melting point and viscosity-average molecular weight of PE wax obtained at different pyrolysis time under 260℃

裂解时间/min	滴熔点/℃	黏均分子量
15	112	4683
30	110	2489
45	108	2135
60	104	1429
120	102	943

Fig.6 Plot of ln(1-α) vs cracking time for LLDPE pyrolysis under different temperatures

Fig.7 Arrhenius equation fitting for pyrolysis reaction of LLDPE k = A 0exp(-E a/RT)

Fig.8 FTIR spectra of PE wax

References 35

1	Panda A K , Singh R K , Dishrag D K . Thermolysis of waste plastics to liquid fuel: a suitable method for plastic waste management and manufacture of value added products—a world prospective [J]. Renewable & Sustainable Energy Reviews, 2010, 14(1): 233-248.
2	Hamad K , Kaseem M , Deri F . Recycling of waste from polymer materials: an overview of the recent works [J]. Polymer Degradation and Stability, 2013, 98(12): 2801-2812.
3	Al-Salem S M , Bumajdad A , Khan A R , et al . Non-isothermal degradation kinetics of virgin linear low density polyethylene (LLDPE) and biodegradable polymer blends[J]. Journal of Polymer Research, 2018, 25: 111-126.
4	Onwudili J A , Insura N , Williams P T . Composition of products from the pyrolysis of polyethylene and polystyrene in a closed batch reactor: effects of temperature and residence time [J]. Journal of Analytical and Applied Pyrolysis, 2009, 86(2): 293-303.
5	Aguado J , Serrano D P , Escola J M . Fuels from waste plastics by thermal and catalytic processes: a review[J]. Ind. Eng. Chem. Res., 2008, 47: 7982-7992.
6	Butler E , Devlin G , McDonnell K . Waste polyolefins to liquid fuels via pyrolysis: review of commercial state-of-the-art and recent laboratory research[J]. Waste Biomass Valor, 2011, 2: 227-255.
7	Hazrat M A , Rasul M G , Khan M M K , et al . Utilization of polymer wastes as transport fuel resources — a recent development[J]. Energy Procedia, 2014, 61: 1681-1685.
8	Arandes J M , Torre I , Castano P , et al . Catalytic cracking of waxes produced by the fast pyrolysis of polyolefins[J]. Energy & Fuels, 2007, 21: 561-569.
9	Ware R L , Rowland S M , Rodgers R P , et al . Advanced chemical characterization of pyrolysis oils from landfill waste, recycled plastics, and forestry residue[J]. Energy & Fuels, 2017, 31: 8210-8216.
10	Murata K , Sato K , Sakata Y . Effect of pressure on thermal degradation of polyethylene[J]. Journal of Analytical and Applied Pyrolysis, 2004, 71(2): 569-589.
11	Al-Salem S M , Lettieri P , Baeyens J . Recycling and recovery routes of plastic solid waste (PSW): a review[J]. Waste Management, 2009, 29: 2625-2643.
12	Sharuddin S D A , Abnisa F , Daud W M A W , et al . A review on pyrolysis of plastic wastes[J]. Energy Conversion and Management, 2016, 115: 308-326.
13	Al-Salem S M , Antelava A , Constantinou A , et al . A review on thermal and catalytic pyrolysis of plastic solid waste (PSW)[J]. Journal of Environmental Management, 2017, 197: 177-198.
14	孙宝国 . 日用化工辞典[M]. 北京: 化学工业出版社, 2005: 115-119.
	Sun B G . Daily Chemical Dictionary[M]. Beijing: Chemical Industry Press, 2005: 115-119.
15	王林, 金秀英, 吴伟, 等 . 微晶蜡和聚乙烯蜡对石蜡性能改进研究[J]. 当代化工, 2018, 47(7): 1383-1386.
	Wang L , Jin X Y , Wu W , et al . Research on performance improvement of paraffin wax with microcrystalline wax and polyethylene wax[J]. Contemporary Chemical Industry, 2018, 47(7): 1383-1386.
16	崔小明 . 聚乙烯蜡的生产及应用前景[J]. 精细与专用化学品, 2014, 22(2): 33-36.
	Cui X M . Production and application prospect of polyethylene wax[J].Fine and Specialty Chemicals, 2014, 22(2): 33-36.
17	Luo C , Ding F , Zhang H , et al . Wax formation study by the pyrolysis of high density polyethylene[J]. Advanced Materials Research, 2012, 418/419/420: 1673-1676.
18	Shang L , Wang S , Zhang Y , et al . Pyrolyzed wax from recycled cross-linked polyethylene as warm mix asphalt (WMA) additive for SBS modified asphalt[J]. Construction and Building Materials, 2011, 25(2): 886-891.
19	王璇, 冀星, 李术元 . 聚乙烯类废塑料制聚乙烯蜡技术进展[J]. 中国工程科学, 2001, 3(12): 90-95.
	Wang X , Ji X , Li S Y . Development of polyethylene wax-making technologies using polyethylene wastes[J]. Engineering Science, 2001, 3(12): 90-95.
20	史建公, 张殿明 . 热降解法制备聚烯烃蜡技术进展[J]. 科技导报, 2008, 26(11): 87-92.
	Shi J G , Zhang D M . Progress on manufacturing polyolefin wax by thermal degradation[J]. Science and Technology, 2008, 26(11): 87-92.
21	徐明星, 胡鹏华 . 一种废旧塑料制取聚乙烯蜡的简易方法: 101885857 B[P]. 2012-07-25.
	Xu M X , Hu P H . A simple method for preparing PE wax from waste plastic: 101885857 B[P]. 2012-07-25.
22	沈劲松, 严宽红, 严柯 . 一种废PE塑料农用薄膜生产氧化聚乙烯蜡的制备方法: 106220758 A[P]. 2016-12-14.
	Shen J S , Yan K H , Yan K . A method for preparing PE wax using waste PE plastic agricultural film: 106220758 A[P]. 2016-12-14.
23	胡浩斌, 罗应军, 杨军 . 响应面法优化废聚乙烯农膜制备聚乙烯蜡的工艺研究[J]. 环境污染与防治, 2015, 37(9): 39-45.
	Hu H B , Luo Y J , Yang J . Optimization of preparation technology of PEW from waste PE agricultural film by response surface methodology[J]. Environmental Pollution & Control, 2015, 37(9): 39-45.
24	Arabiourrutia M , Elordi G , Lopez G , et al . Characterization of the waxes obtained by the pyrolysis of polyolefin plastics in a conical spouted bed reactor[J]. Journal of Analytical and Applied Pyrolysis, 2012, 94: 230-237.
25	Salmiaton A , Garforth A . Waste catalysts for waste polymer[J]. Waste Management, 2007, 27: 1891-1896.
26	王吉林, 王璐璐, 周萍 . 溶剂辅助聚乙烯废塑料裂解制聚乙烯蜡[J]. 现代塑料加工应用, 2010, 22(2): 32-35.
	Wang J L , Wang L L , Zhou P . Production of polyethylene wax from PE waste plastic by solvent supporting pyrolysis[J]. Modern Plastics Processing Applications, 2010, 22(2): 32-35.
27	梅涛, 迟姚玲, 易玉峰, 等 . 高密度聚乙烯热解生成聚乙烯蜡及产品的性质研究[J]. 石油炼制与化工, 2011, 42(11): 66-69.
	Mei T , Chi Y L , Yi Y F , et al . Study on the preparation and properties of polyethylene wax from pyrolysis of high density polyethylene[J]. Petroleum Processing and Petrochemicals, 2011, 42(11): 66-69.
28	袁倩, 王璐璐, 封瑞江, 等 . PE废塑料溶剂裂解制备聚乙烯蜡[J]. 化学工程师, 2015, 5(5): 1-7.
	Yuan Q , Wang L L , Feng R J , et al . Preparation of polyethylene wax from waste PE plastics by solvent pyrolysis[J]. Chemical Engineer, 2015, 5(5): 1-7.
29	张建雨, 于硕, 冯跃跃, 等 . 废旧聚乙烯催化降解制备聚乙烯蜡[J]. 塑料科技, 2010, 38: 51-54.
	Zhang J Y , Yu S , Feng Y Y , et al . Study on PE wax prepared through cracking waste PE[J]. Plastic Science and Technology, 2010, 38: 51-54.
30	左禹, 丁艳军, 朱琳, 等 . 小型固定床实验台条件下的聚乙烯热解[J]. 清华大学学报 (自然科学版), 2015, 45(11): 1544-1548.
	Zuo Y , Ding Y J , Zhu L , et al . Analysis of polyethylene pyrolysis using a bench scale fixed bed[J]. Journal of Tsinghua University (Science and Technology), 2015, 45(11): 1544-1548.
31	张振量, 王禹, 项素云, 等 . 聚乙烯蜡的性能及应用[J]. 塑料科技, 2002, (6): 50-53.
	Zhang Z L , Wang Y , Xiang S Y , et al . Application and properties of polyethylene wax[J]. Plastic Science and Technology, 2002, (6): 50-53.
32	冀星, 钱家麟, 王剑秋 . 聚乙烯聚丙烯树脂及废料的热解[J]. 环境科学, 1999, (5): 82-85.
	Ji X , Qian J L , Wang J Q . The pyrolysis of polyethylene polypropene and its wastes[J]. Environmental Science, 1999, (5): 82-85.
33	Jeon J K , Park Y K . Pyrolysis of an LDPE-LLDPE-EVA copolymer mixture over various mesoporous catalysts[J]. Korean Journal of Chemistry Engineering, 2000, 17(5): 489-496.
34	Miteva K , Slavcho K , Bogoeva-Gaceva G . Kinetic analysis of pyrolysis of waste polyolefin mixture[J]. Arabian Journal for Science and Engineering, 2016, 41: 2601-2609.
35	Al-Salem S M , Lettieri P . Kinetic study of high density polyethylene (HDPE) pyrolysis[J]. Chemical Engineering Research and Design, 2010, 88: 1599-1606.

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