基于熔融盐催化体系天然气裂解制氢联产碳材料

doi:10.16085/j.issn.1000-6613.2024-1427

摘要/Abstract

摘要：

在“双碳”背景下，氢能因其绿色低碳、单位质量能量密度高等特点，被认为是实现“双碳”目标的重要保障。然而，以化石能源制氢以及电解水制氢受高碳排放或高成本制约，限制了其大规模应用。因而，开发低碳、低成本制氢技术势在必行。熔融法天然气裂解技术实现了氢气和碳材料联产，且不产生CO₂排放，经济和环境效益明显。本文合成了一种二元熔融盐催化介质，实现了碳纳米管与氢气联产，甲烷单程转化率可达30%，产出气中氢气质量分数大于40%。研究发现高温、低流速、低浓度原料气均有助于提升原料气转化率以及碳材料品质，例如原料气质量分数由100%降低至25%，转化率可提升至48%，制得的碳纳米管品质更加均匀细长，然而低浓度原料气（氮气调节）会使得产品气中氢气浓度稀释，未来可考虑采用氢气调节原料气浓度来加以改善。且均匀的气泡分散可以增大气液接触面积，延长气泡停留时间，减少未经催化反应杂质碳的生成。此外，相关裂解反应机理本文也有涉及。

关键词: 熔融盐, 天然气裂解, 氢, 碳纳米管

Abstract:

Under the background of "carbon peaking and carbon neutralization", hydrogen energy is recognized as an important guarantee to achieve the goal of "double carbon" because of its green, low carbon and high energy density per unit mass. However, the large-scale application of hydrogen production from fossil energy and electrolytic water is limited by high carbon emissions or high costs. Therefore, it is imperative to develop low-carbon and low-cost hydrogen production technology. Molten metal methane pyrolysis technology achieves co-production of hydrogen gas and carbon materials without CO₂ emissions, demonstrating significant economic and environmental benefits. In this paper, a binary molten salt catalytic medium was synthesized to realize the co-production of carbon nanotubes and hydrogen. The single-pass conversion rate of methane could reach 30% and the hydrogen concentration in the output gas exceed 40%. The study found that high temperatures, low flow rates and the low concentration of raw gases all contributed to improving the conversion rate of the raw gases and the quality of the carbon materials. For instance, reducing the feed gas concentration from 100% to 25% can increase the conversion rate to 48%, resulting in the carbon nanotubes with more uniform and slender quality. However, the low concentration of feed gas (regulated by nitrogen) would dilute the hydrogen concentration in the product gas, which can be improved by adjusting the feed gas concentration with hydrogen in the future. Furthermore, uniform bubble dispersion can be relied on to increase the gas-liquid contact area, extend bubble residence time and reduce the formation of impurity carbon not involved in catalytic reactions. Additionally, the relevant cracking reaction mechanism was also involved in this paper.

Key words: molten salts, methane cracking, hydrogen, carbon nanotubes

中图分类号:

TE09

何阳东, 周理, 杨威, 王露, 覃莉. 基于熔融盐催化体系天然气裂解制氢联产碳材料[J]. 化工进展, 2025, 44(10): 5838-5847.

HE Yangdong, ZHOU Li, YANG Wei, WANG Lu, QIN Li. Hydrogen and carbon co-production from natural gas pyrolysis based on molten salt catalytic system[J]. Chemical Industry and Engineering Progress, 2025, 44(10): 5838-5847.

图/表 18

表1 典型制氢技术的能耗和碳排放强度对比

工艺路线	技术成熟度	能耗/kW·h·kg^-1 $H 2$	碳排放/kg $C O 2$ ·kg^-1 $H 2$
煤制氢	成熟	5.5	19
天然气制氢	成熟	5.7	10
工业副产氢	成熟	4.8	5
电解水制氢	初步成熟	39	—

表1 典型制氢技术的能耗和碳排放强度对比

工艺路线	技术成熟度	能耗/kW·h·kg^-1 $H 2$	碳排放/kg $C O 2$ ·kg^-1 $H 2$
煤制氢	成熟	5.5	19
天然气制氢	成熟	5.7	10
工业副产氢	成熟	4.8	5
电解水制氢	初步成熟	39	—

图1 熔融法天然气裂解氢碳联产工艺示意

图2 实验装置流程示意

图3 碳材料纯化处理示意

图4 裂解温度对甲烷催化裂解性能影响

图5 碳材料性能表征结果

图6 原料气流量及反应温度对催化裂解性能影响

图7 气泡从管口处脱离过程示意

图8 原料气流量对碳材料形貌影响

图9 原料气浓度对甲烷裂解性能影响

图10 不同原料气浓度制得的碳材料扫描电镜

图11 不同浓度下碳材料拉曼表征

图12 不同曝气方式效果

表2 管径设置参数

温度/℃	CH₄质量分数/%	进气流速/mL·min^-1	反应管材质	分散条件
1000	50	90	刚玉管	单孔进气管
1000	50	90	刚玉管	四孔进气管
1000	50	90	刚玉管	孔径100~300µm的石英曝气管

图13 输气管孔径对甲烷裂解性能影响

图14 气泡分散对碳材料品质影响

图15 裂解反应温度对中间产物的影响

图16 单组分A催化体系（蓝色）以及A-B二元催化体系（红色）吉布斯自由能

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