Microwave assisted co-pyrolysis of waste polypropylene /activated carbon to produce combustible pyrolysis gas and light pyrolysis oil

doi:10.16085/j.issn.1000-6613.2021-2660

Abstract

Abstract:

In order to realize the resource utilization of waste plastics, this paper adopted microwave co-pyrolysis method, selected waste polypropylene (PP) as pyrolysis raw material and the granular activated carbon as the absorbing material to produce combustible pyrolysis gas and light pyrolysis oil. The effects of microwave power on pyrolysis gas, pyrolysis oil and solid carbon residue obtained from pyrolysis without adding catalyst and with addition of different kinds of metal oxides as auxiliary catalysts were studied. In addition, the effects of power and the additions of MgO and ZnO on the products were also investigated in detail. The results showed that the yield of pyrolysis gas without adding catalyst was more than 40% in which H₂ and CH₄ accounted for about 40% of the total gas volume, while the yield of pyrolysis oil was about 40% and the yield of solid carbon was about 15%. The total content of alkanes, olefins and monocyclic aromatic hydrocarbons in pyrolysis oil can reach more than 90%, and the proportion of pyrolysis oil was between 0.7 and 0.8, which belonged to light pyrolysis oil. After adding different metal oxides, some metal oxides can deepen the pyrolysis degree of PP. Among them, MgO can significantly increase the content of CH₄, and ZnO can significantly increase the content of H₂. The metal oxides can further increase the content of monocyclic aromatic hydrocarbons in the pyrolysis oil. According to the response surface analysis, the optimal pyrolysis conditions for PP were as follows. After adding MgO, the power range was 660—720W with amount of catalyst of 0.6—1g. After adding ZnO, the power range was 680—740W with amount of catalyst of 0.4—1g.

Key words: microwave co-pyrolysis, polypropylene waste plastics, activated carbon, metal oxide

摘要：

为实现对废旧塑料的资源化利用，本文采用微波裂解法，以废弃聚丙烯（PP）为裂解原料、颗粒状活性炭为吸波材料通过微波共裂解制取可燃裂解气与轻质裂解油。实验研究了不添加催化剂时微波功率对裂解所得裂解气、裂解油和固体碳的影响，以及添加不同种类金属氧化物作为辅助催化剂时对裂解产物的影响，并详细研究了MgO、ZnO的添加量和功率对产物的影响。研究发现，不添加催化剂时裂解气的产率可达40%，其中H₂、CH₄约占气体总体积的40%，裂解油的产率为40%左右，固体碳的产率为15%左右。裂解油中烷烃、烯烃和单环芳烃三者的总含量可达90%以上，裂解油的相对密度介于0.7~0.8之间，属于轻质裂解油；添加不同金属氧化物后部分金属氧化物可加深PP的裂化程度，其中MgO可显著提高CH₄的含量，ZnO可显著提高H₂的含量，且金属氧化物可进一步提高裂解油中单环芳烃的含量；结合响应面分析PP的最佳裂解条件为：加入MgO后功率范围在660~720W，催化剂量在0.6~1g；加入ZnO后功率范围在680~740W，催化剂量在0.4~1g。

关键词: 微波共裂解, 废旧聚丙烯塑料, 活性炭, 金属氧化物

CLC Number:

TQ322

LIU Nan, HU Yiming, YANG Ying, LI Hongjin, GAO Zhuqing, HAO Xiuli. Microwave assisted co-pyrolysis of waste polypropylene /activated carbon to produce combustible pyrolysis gas and light pyrolysis oil[J]. Chemical Industry and Engineering Progress, 2022, 41(S1): 150-159.

刘楠, 胡一铭, 杨颖, 李红晋, 高竹青, 郝秀丽. 废旧聚丙烯/活性炭微波共裂解制取可燃裂解气与轻质裂解油[J]. 化工进展, 2022, 41(S1): 150-159.

Figures/Tables 26

功率 /W	裂解气质量 /g	裂解气产率（质量分数）/%	裂解油质量 /g	裂解油产率（质量分数）/%	固体碳质量 /g	固体碳产率（质量分数）/%
500	—	—	—	—	—	—
600	8.95	44.75	7.92	39.60	3.13	15.65
700	8.35	41.75	8.84	44.20	2.81	14.05
800	10.05	52.25	6.98	34.90	2.97	14.85

功率/W	$V H 2 / %$	$V C H 4 / %$	$V H 2 + C H 4 / %$
500	—	—	—
600	16.77	24.80	41.57
700	18.13	24.09	42.22
800	23.04	27.09	50.13

功率/W	$V H 2 / %$	$V C H 4 / %$	$V H 2 + C H 4 / %$
500	—	—	—
600	16.77	24.80	41.57
700	18.13	24.09	42.22
800	23.04	27.09	50.13

金属氧化物	裂解气质量/g	裂解气产率（质量分数）/ %	裂解油质量/g	裂解油产率（质量分数）/ %	固体碳质量 /g	固体碳产率（质量分数）/%
无催化剂	8.35	41.75	8.84	44.20	2.81	14.05
CaO	8.60	43.00	9.05	45.25	2.35	11.75
TiO₂	7.49	37.45	9.22	46.10	3.29	16.45
Fe₂O₃	9.75	48.75	8.18	40.90	2.07	10.35
Al₂O₃	8.97	44.85	8.88	44.40	2.15	10.75
MgO	10.49	52.45	7.92	39.60	1.59	7.90
ZnO	10.05	50.25	7.73	38.65	2.22	11.10
MoO₃	9.20	46.00	8.21	41.05	2.59	12.95

催化剂	相对密度
无	0.806
CaO	0.723
Al₂O₃	0.750
TiO₂	0.790
MoO₃	0.776
ZnO	0.720
Fe₂O₃	0.760
MgO	0.753

功率/W	MgO质量 /g	PP∶MgO （质量比）	裂解气质量 /g	裂解气产率（质量分数）/%	裂解油质量 /g	裂解油产率（质量分数）/%	固体碳质量 /g	固体碳产率（质量分数）/%
600	0.2	100∶1	8.64	43.20	7.57	37.85	3.79	18.95
600	0.4	50∶1	9.86	49.30	7.03	35.13	3.11	15.55
600	1.0	20∶1	9.94	49.70	7.56	37.80	2.50	12.50
700	0.2	100∶1	10.01	50.05	7.50	37.50	2.49	12.45
700	0.4	50∶1	10.07	50.35	7.69	38.45	2.24	11.20
700	1.0	20∶1	10.49	52.45	7.92	39.60	1.59	7.90
800	0.2	100∶1	9.11	43.55	9.13	45.65	1.76	8.80
800	0.4	50∶1	8.83	44.15	9.02	45.10	2.15	10.75
800	1.0	20∶1	8.70	43.50	9.13	45.65	2.17	10.85

功率/W	ZnO质量 /g	PP∶ZnO （质量比）	裂解气质量 /g	裂解气产率（质量分数）/%	裂解油质量 /g	裂解油产率（质量分数）/%	固体碳质量 /g	固体碳产率（质量分数）/%
600	0.2	100∶1	7.52	37.60	8.28	41.40	4.20	21.00
600	0.4	50∶1	7.49	37.45	9.22	46.10	3.29	16.45
600	1.0	20∶1	8.23	41.15	8.71	43.55	3.06	15.30
700	0.2	100∶1	9.34	46.70	8.52	42.60	2.14	10.70
700	0.4	50∶1	9.70	48.50	7.80	39.00	2.50	12.50
700	1.0	20∶1	10.05	50.25	7.73	38.65	2.22	11.10
800	0.2	100∶1	9.18	45.90	8.82	44.10	2.00	10.00
800	0.4	50∶1	8.66	43.30	9.22	46.10	2.12	10.60
800	1.0	20∶1	9.10	45.50	8.26	41.30	2.64	13.20

功率r/W	催化剂质量/g	ZnO相对密度	MgO相对密度
600	0.2	0.776	0.750
600	0.4	0.780	0.750
600	1.0	0.776	0.740
700	0.2	0.750	0.792
700	0.4	0.760	0.793
700	1.0	0.720	0.753
800 800 800	0.2 0.4 1.0	0.780 0.777 0.779	0.771 0.772 0.760

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