NPC deputy, a chemist, publishes breakthrough for oil industry

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NPC deputy, a chemist, publishes breakthrough for oil industry

2016-03-07 09:32

China Daily Editor: Qian Ruisha

Bao Xinhe, a physical chemist from the Dalian Institute of Chemical Physics affiliated with the Chinese Academy of Sciences and a National People's Congress deputy, reported a revolutionary chemical processing method that could make the country's basic chemical materials more affordable and eco-friendly.[Special coverage]

The research, which reported a new reaction process to convert coals into olefins, was published over the weekend by Science magazine and stirred attention among the international scientific community.

"Olefins are known as the mother of petrochemicals, and are important intermediates in the production of plastic and medicines. The production capacity of olefins, to some extent, represents the development level of a country's chemical industry," said Wang Zizong, assistant chief engineer at Sinopec Group, one of the nation's top producers of crude oil.

Olefins can be produced from petroleum, coal, natural gas or biomass via synthesis gas (a mixture of carbon monoxide and hydrogen).

"Due to China's limited petroleum, last year we only produced 42 million tons of olefins, 60 percent of the domestic demand," Wang said. "That is why we need new technologies to produce olefins from other feedstocks."

As early as 1923, Franz Fischer and Hans Tropsch of the Max Planck Institute for Coal Research in Germany had developed a technology for converting coal into liquid hydrocarbons using metal catalysts - so-called Fischer-Tropsch synthesis - which was extensively used in industrial applications and has been constantly improved over the past century by scientists worldwide. However, conversion of synthesis gas directly to light olefins via Fischer-Tropsch synthesis technology remains limited.

The new process reported by Bao's team used a bifunctional catalyst containing partially reduced metal oxides and zeolite, which selectively converted synthesis gas to light olefins.

A review by Krijn P. de Jong from Utrecht University in the Netherlands said the research "should be of interest to both academia and industry". The review also appeared in Science on Friday. "The new process could become a serious competitor for industrial processes such as FTO (Fischer-Tropsch to olefins) and MTO (methanol to olefins)," de Jong wrote.

Currently Bao and his team are trying to extend the fundamental study to explore possible industrial applications.

"Back in June 2014, President Xi Jinping said the country needed a revolution in energy technology, together with related industries as a new driving force. From my point of view, the technological revolution should be combined with China's actual conditions," Bao said.

"While the U.S. focuses on unconventional gas resources, the EU emphasizes renewable energy. We should fully understand the major energy challenge we are facing," he said, adding that development should focus on "technologies for the coal-based chemical industry"

NPC deputy, a chemist, publishes breakthrough for oil industry

 

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Surprised by selectivity

Krijn P. de Jong
Science 04 Mar 2016:

Summary

Lower olefins, particularly ethylene (C2H4), propylene (C3H6), and butylene (C4H8), are important intermediates in the manufacture of products such as plastics, solvents, paints, and medicines. They are produced worldwide in amounts exceeding 200 million tons per year (see the photo) (1), mostly from crude oil. More recent approaches use methanol or synthesis gas (syngas; a mixture of carbon monoxide and hydrogen) as feedstocks, but capital investments are high and/or selectivities to lower olefins limited. A bifunctional catalyst reported by Jiao et al. on page 1065 of this issue (2) enables the direct conversion of synthesis gas to lower olefins with a surprisingly high selectivity.

Surprised by selectivity | Science

A more detailed report in Chinese：

Science杂志发表包信和院士潘秀莲研究员团队
煤气化直接制烯烃研究成果

来源：中国科学院大连化学物理研究所发布时间：2016-03-05

近日，由中国科学院大连化学物理研究所（以下简称“大连化物所”）包信和院士（现任复旦大学常务副校长）和潘秀莲研究员领导的团队颠覆了90多年来煤化工一直沿袭的费托（简称为F-T）路线，创造性地直接采用煤气化产生的合成气（纯化后CO和H2的混合气体），在一种新型复合催化剂的作用下，高选择性地一步反应获得低碳烯烃。该研究成果于3月4日在美国《科学》（Science）杂志上发表，过程已申报中国发明专利和国际PCT专利。这项成果被同行誉为“煤转化领域里程碑式的重大突破”。

德国科学家Fischer（费舍尔）和Tropsch（托普希）于1923年发明了煤经合成气生产高碳化学品和液体燃料的费-托（F-T）过程。尽管该过程并不完美，比如，除产生大量的二氧化碳以外，还消耗大量的水，且产物选择性差，后续处理消耗大量的能量，然而国际能源和化工界却一直认为该过程不可替代。如今，这一过程被中科院大连化物所的研究人员颠覆——他们摒弃了高水耗和高能耗的水煤气变换制氢过程，直接采用煤气化产生的混合气体（经纯化），高选择性地获得低碳烯烃。当CO单程转化率为17%时，低碳烃类产物的选择性达到94%，其中低碳烯烃（乙烯、丙烯和丁烯）的选择性大于80%。打破了传统费-托合成过程低碳烯烃的选择性最高为58%的极限（SF极限）。

传统的费-托（F-T）过程采用金属（还原态）作催化剂。CO分子在金属催化剂表面被活化解离成C原子和O原子，C原子和O原子与吸附在催化剂表面的氢发生反应，形成亚甲基（CH2）中间体，同时放出水分子。亚甲基中间体通过迁移插入反应，在催化剂表面进行自由聚合，生成含不同碳原子数（从一到三十，有时甚至到上百个碳原子）的烃类产物。整个反应烃类产物碳原子数分布广，目标产物的选择性低。同时，这一过程需要消耗大量氢气来移去金属催化剂表面CO解离生成的O原子，而这些宝贵的氢气是通过水煤气变换（CO+H2OH2+CO2）获得的，水煤气变换过程是一个高能耗的过程，还要释放出大量CO2。大连化物所研究人员创制的过程采用部分还原的复合氧化物作催化剂，CO分子在催化剂氧缺陷位上吸附并解离，气相氢分子选择性地与解离生成的C原子反应生成亚甲基自由基，而催化剂表面CO解离生成的氧原子倾向于与另一个CO反应，形成CO2。与传统的F-T过程不同，在氧缺陷位产生的亚甲基自由基，不在催化剂表面停留或发生表面聚合反应，而是迅速进入分子筛孔道，在孔道限域环境中进行择形偶联反应，定向生成低碳烯烃，大大提高了产物的选择性。通过对分子筛孔道和酸性质的调控，可以实现产物分子的可控调变。

这一突破，通过以CO替代H2来消除烃类形成中多余的氧原子，在反应不改变CO2总排放的情况下，摒弃了高耗能和高耗水的水煤气变换反应，从原理上开创了一条低耗水（结构上没有水循环）进行煤转化的新途径，成功地回答了李克强总理一直关心的“能不能不用水或少用水进行煤化工”的问题。同时，通过创造性将氧化物催化剂与分子筛复合，巧妙地实现了CO活化和中间体偶联等两种催化活性中心的有效分离，把传统费托技术上“漫无目的、无拘无束”生长的“自由基”控制在一个“笼子”（分子筛）里，通过限制其行为，使其最终变成我们想要的目标产物（低碳烯烃）。破解了传统催化反应中活性与选择性此长彼消的“跷跷板”难题，为高效催化剂和催化反应过程的设计提供了指南。

新发明的过程除了节水和在工艺上降低CO2排放（缩短流程、降低能耗）外，还具有很高的经济效益。据中国石化工程建设有限公司（SEI）初步评估，在现有的条件下，该过程的内部收益率（IRR）可达14%以上。国内外多家化学公司都非常感兴趣该过程的进一步应用推广。经认真评估和协商，目前大连化物所已与国内重要化工企业和国外著名化学公司达成初步协议，着手在催化剂制备和工艺过程开发等方面共同合作，力争尽快实现工业示范和产业化，努力将这一原创性成果转变为真正的生产力。

当从事费托过程制烯烃（FTTO）研究二十多年的德国BASF公司专家Schwab博士了解到这一过程的基本情况后，沮丧地说：“这个点子为什么不是我们先想到的？”包信和院士不无自豪地回答道：“你们想到的点子已经很多了，也该轮到我们了”。说这话的底气来自于一个优秀的研究团队几十年的坚守和中国日益提高的科技研究能力的支撑：仅仅这一项研究，该团队就耗费了九年多的时间，并与国内包括合肥同步辐射光源在内的多家科研单位合作，使用了多种自主研制的高端研究装置。在这期间，团队除了申报了多件中国发明专利和国际PCT专利以外，没有公开发表一篇相关研究的文章。

相关项目的研究得到了国家自然科学基金委员会、科学技术部和中国科学院战略性先导科技专项的资助。（文/图 姜秀美、焦峰）


Science杂志发表包信和院士潘秀莲研究员团队煤气化直接制烯烃研究成果_学校要闻_复旦大学

 

[JSCh]

Science 04 Mar 2016:
Vol. 351, Issue 6277, pp. 1065-1068
DOI: 10.1126/science.aaf1835

Small olefins from syngas
The conversion of coal or natural gas to liquid fuels or chemicals often proceeds through the production of CO and H2. This mixture, known as syngas, is then converted to hydrocarbons with Fischer-Tropsch catalysts. For the light olefins (ethylene to butylenes) needed for chemical and polymer synthesis, conventional catalysts are mechanistically limited to <60% conversion and deactivate through carbon buildup. Jiao et al. developed a bifunctional catalyst that achieves higher conversions and avoids deactivation (see the Perspective by de Jong). A zinc-chromium oxide creates ketene intermediates that are then coupled over a zeolite.

Science, this issue p. 1065, see also p. 1030

Abstract
Although considerable progress has been made in direct synthesis gas (syngas) conversion to light olefins (C2=–C4=) via Fischer-Tropsch synthesis (FTS), the wide product distribution remains a challenge, with a theoretical limit of only 58% for C2–C4 hydrocarbons. We present a process that reaches C2=–C4= selectivity as high as 80% and C2–C4 94% at carbon monoxide (CO) conversion of 17%. This is enabled by a bifunctional catalyst affording two types of active sites with complementary properties. The partially reduced oxide surface (ZnCrOx) activates CO and H2, and C−C coupling is subsequently manipulated within the confined acidic pores of zeolites. No obvious deactivation is observed within 110 hours. Furthermore, this composite catalyst and the process may allow use of coal- and biomass-derived syngas with a low H2/CO ratio.

Selective conversion of syngas to light olefins | Science