Catalytic Effects of Fe- And Ca-Based Additives on Gas Evolution During Pyrolysis of Dachengzi Oil Shale of China

Abstract

The pyrolysis of Dachengzi oil shale (OS), Huadian City, China, was carried out in a stainless-steel cylindrical retort at 520 °C both in the absence and presence of catalyst under argon atmosphere to evaluate the catalytic effects of Fe 2 O 3 and CaCO 3 additives on the products yield and characteristics of non-condensable gases. The results showed that the catalyst significantly affected the reactivity of OS kerogen pyrolysis. The shale oil yield increased after adding the catalyst, especially Fe 2 O 3 , but the shale char yield decreased in the presence of the catalyst. The noncondensable gases yield rose in the CaCO 3-catalysed pyrolysis and declined upon the Fe 2 O 3-catalysed process, indicating that CaCO 3 had a more pronounced catalytic effect on the secondary reactions of oil vapors. In addition, the gaseous products obtained both with and without the catalyst had a higher volume content of CO 2 , CH 4 and H 2 , and a lower volume content of CO and C 2-C 4 hydrocarbons. The peak concentrations of CO 2 and H 2 increased in the presence of the catalyst, especially Fe 2 O 3 , while that of CO enhanced with addition of CaCO 3 as a catalyst. H 2 was generated at higher temperature compared to CO 2 and CO. Furthermore, Fe 2 O 3 and CaCO 3 exhibited different effects on the evolution of C 1-C 4 hydrocarbons. COS and H 2 S evolved almost simultaneously, the amount of H 2 S released being higher than that of COS. The peak concentrations of the said gases decreased with adding the catalyst, especially Fe 2 O 3. The non-condensable gases produced both before and after catalysis mainly consisted of CO 2 and CH 4 , and some minor gases, in terms of mass distribution. The mass contents of ethane, butane, CO 2 and H 2 increased after the use of the catalyst, while those of butane, H 2 S and COS decreased. Moreover, adding Fe 2 O 3 and CaCO 3 resulted in the decline in the ethene/ethane and propene/propane ratios, respectively, suggesting that different catalysts possibly led to different changes in the physical structure of oil shale and then caused the secondary reactions of pyrolysis products to proceed to different extents.

A review on thermogravimetric analysis‐based analyses of the pyrolysis kinetics of oil shale and coal

“…93 Wang et al added CaCO 3 and Fe 2 O 3 to kerogen pyrolysis and found that Fe 2 O 3 can increase shale oil yield and reduce gas phase product yield and CaCO 3 can catalyze the secondary cracking of products. 94 Williams and Chishti found that the addition of ZSM-5 increased gas production of oil shale pyrolysis, but the yield of shale oil decreased. The content of polycyclic aromatic hydrocarbons in the oil phase increased, while the content of N and S decreased.…”

“…Yu et al discovered that Co can accelerate the cleavage of C–C bonds in organic compounds, improve the selectivity of aromatic hydrocarbons and promote the aromatization of olefins, thus increasing the content of olefins and aromatic hydrocarbons 93 . Wang et al added CaCO 3 and Fe 2 O 3 to kerogen pyrolysis and found that Fe 2 O 3 can increase shale oil yield and reduce gas phase product yield and CaCO 3 can catalyze the secondary cracking of products 94 . Williams and Chishti found that the addition of ZSM‐5 increased gas production of oil shale pyrolysis, but the yield of shale oil decreased.…”

Progress in Catalytic Pyrolysis of Oil Shale

“…Therefore, the effect of metal compounds on the yield and quality of liquid products has been studied extensively. Studies have found that Fe, Ca, Zn, Ni, and other metal oxides and chloride can accelerate the pyrolysis of oil shale and promote the generation of hydrogen-free radicals and the lightening of shale oil [ 24 ].…”

“…After the Fe 2 O 3 catalyst was added and the CaCO 3 catalyst was added, the shale oil yield also increased in the pyrolysis process, but the shale oil yield was 1.02 times and 1.01 times, respectively. Therefore, Fe 2 O 3 has a stronger catalytic effect on oil shale pyrolysis [ 24 ]. Lu et al [ 12 ] selected CH 3 COONa, (CH 3 COO) 2 Ca, and MgO as oil shale catalysts to study their pyrolysis behavior and characteristics of pyrolysis products.…”

Investigation on the Catalytic Cracking Mechanism of CuO on Dimethyl Sulfoxide (C2H6OS) and Surface Modification Effects: Insights from Density Functional Theory Calculations

“…In our recent theoretical study on the catalytic activity of Cu-doped SBA-15 molecular sieves, we found that the decomposition of organic sulfur compounds can be promoted by doping with Cu [7]. Moreover, research [8] has shown that Fe, Ca, Zn, Ni, and other metal oxides and chloride expedite the pyrolysis of oil shale, facilitate the generation of hydrogen-free radicals, and cause the shale oil to become lighter. Lu et al [9] used MgO as a catalyst to investigate the catalytic pyrolysis of Changji oil shale in Xinjiang and found that the addition of MgO increased the yields of olefins and shale gas CH 4 in shale oil.…”