Adsorption,selectivity,and phase behavior in organic nanopores for shale gas and oil development

In a shale gas and oil reservoir,hydrocarbon fluids are stored in organic nanopores with sizes on the order of~1-100 nm.The adsorption,selectivity,and phase behavior of hydrocarbons in the nanopores are crucial for estimating the gas-in-place and predicting the productivity.In this study,to understand the characteristics of the phase behavior of multicomponent hydrocarbon systems in shale reservoirs,the phase behavior of a CH_(4)/n-C_(4)H_(10)binary mixture in graphite nanopores was investigated by Grand Ca-nonical Monte Carlo(GCMC)molecular simulation.The method for determining the dew-point pressure and bubble-point pressure in the nanopores was explored.The condensation phenomenon was observed owing to the difference in the adsorption selectivities of the hydrocarbon molecules on the nanopore surfaces,and hence the dew-point pressure(and bubble-point pressure)of hydrocarbon mixtures in the nanopores significantly shifted.The GCMC simulations reproduced both the higher and lower bubble-point pressures in nanopores in previous studies.This work highlights the crucial role of the selec-tivity in the phase behavior of hydrocarbons in nanopores.

A pillared-layer metal-organic framework for efficient separation of C_(3)H_(8)/C_(2)H_(6)/CH_(4) in natural gas

Metal-organic frameworks(MOFs)have great potentials as adsorbents for natural gas purification.However,the trade-off between selectivity and adsorption capacity remains a challenge.Herein,we report a pillared-layer metal-organic framework Ni(HBTC)(bipy)for efficiently separating the C_(3)H_(8)/C_(2)H_(6)/CH_(4) mixture.The experimental results show that the adsorption capacity of C_(3)H_(8) and C_(2)H_(6) on Ni(HBTC)(bipy)are as high as 6.18 and 5.85 mmol·g^(-1),while only 0.93 mmol·g^(-1) for CH_(4) at 298 K and 100 kPa.Especially,the adsorption capacity of C_(3)H_(8) at 5 kPa can reach an unprecedented 4.52 mmol·g^(-1) and for C_(2)H_(6) it is 1.48 mmol·g^(-1) at 10 kPa.The ideal adsorbed solution theory predicted C_(3)H_(8)/CH_(4) selectivity is as high as 1857.0,superior to most of the reported materials.Breakthrough experiment results indicated that material could completely separate the C_(3)H_(8)/C_(2)H_(6)/CH_(4) mixture.Therefore,Ni(HBTC)(bipy)is a promising material for separation of natural gas.

盐湖提锂尾液中锂回收的吸附试验研究

从高镁锂比盐湖提锂生产尾液中回收锂,可实现锂资源高效回收利用,对企业经济效益的提高具有重要意义。以东台吉乃尔盐湖提锂尾液为原料,系统性研究了铝系层状锂吸附剂JW-LAHS对提锂尾液中锂的静态、动态吸附和解吸过程。结果表明,吸附剂的静态吸附容量为7.3 mg/g,镁锂分离因子为27.98;最佳动态吸附条件为床层高度24.8 cm,进料流速3.5 mL/min,此时穿透时间为22.0 min,Li+吸附率大于95%,饱和时间为210 min,饱和吸附容量达到5.5 mg/g,表明锂吸附剂适合从高镁锂比提锂尾液中回收锂。BDST模型能够准确预测床层穿透时间,误差小于8.61%。使用去离子水进行解吸,增大解吸流速能够加速Li+脱出,但对Mg^(2+)的解吸无明显影响。解吸流速为4.6 mL/min,解吸360 min时,Li+解吸率为83.25%,总解吸液的镁锂比值为0.7,仅为提锂尾液(80)的0.88%。循环20次后吸附容量仍能保持原来的82%以上,表明锂吸附剂循环稳定性良好。

Insight into the selective separation of CO_(2)from biomass pyrolysis gas over metal-incorporated nitrogen-doped carbon materials:a first-principles study

The composition of biomass pyrolysis gas is complex,and the selective separation of its components is crucial for its further utilization.Metal-incorporated nitrogen-doped materials exhibit enormous potential,whereas the relevant adsorption mechanism is still unclear.Herein,16 metal-incorporated nitrogen-doped carbon materials were designed based on the density functional theory calculation,and the adsorption mechanism of pyrolysis gas components H2,CO,CO_(2),CH_(4),and C2H6 was explored.The results indicate that metal-incorporated nitrogen-doped carbon materials generally have better adsorption effects on CO and CO_(2)than on H_(2),CH_(4),and C_(2)H_(6).Transition metal Mo-and alkaline earth metal Mg-and Ca-incorporated nitrogen-doped carbon materials show the potential to separate CO and CO_(2).The mixed adsorption results of CO_(2)and CO further indicate that when the CO_(2)ratio is significantly higher than that of CO,the saturated adsorption of CO_(2)will precede that of CO.Overall,the three metal-incorporated nitrogen-doped carbon materials can selectively separate CO_(2),and the alkaline earth metal Mg-incorporated nitrogen-doped carbon material has the best performance.This study provides theoretical guidance for the design of carbon capture materials and lays the foundation for the efficient utilization of biomass pyrolysis gas.

改性大洋富钴结壳选矿尾矿对重金属离子的吸附选择性研究

采用静态吸附法研究了改性前后大洋富钴结壳选矿尾矿,在相同条件下对模拟废水中Cu2+、Pb2+、Zn2+、Cd2+等重金属离子的单独和混合吸附特性。结果表明:①单独吸附效果的顺序为Pb2+>Cd2+>Cu2+>Zn2+;②当Pb2+、Cd2+、Cu2+和Zn2+同时存在时,吸附效果的顺序是Pb2+>Cu2+>Cd2+>Zn2+或Pb2+>Cd2+>Cu2+>Zn2+,并且离子初始浓度越大,Pb2+与其它共存的重金属离子的选择性分离效果越好;③改性大洋富钴结壳选矿尾矿对重金属离子选择性吸附效果好,成本低,制备工艺简单。

Retention mechanism of phenol in mainstream cigarette smoke by cellulose acetate filters

To understand the retention mechanism of phenol in mainstream cigarette smoke by cellulose acetate(CA)filters,the phenol filtration efficiency,the phenol distribution in the gas phase and particulate phase during filtration and the retention characteristics of the filter for both the gas phase and particulate phenol species were investigated.The distribution of particulate bound phenol as a function of the particle size was examined.The ratio of phenol transferring from the particulate phase to the gas phase during smoke flowing through the CA filter were studied.Retention mechanisms for phenol in the gas phase as well as particulate phase phenol in the filter and the phase transition of phenol were proposed.Phenol filtration efficiency of the cigarette filter was calculated based on the proposed retention mechanisms and compared with available experimental data.The results showed that:1)Comparing with nicotine and the other particulate bound smoke constituents,CA filter exhibited a certain retention selectivity for phenol.2)Although phenol was mainly bound to the particulate phase of the cigarette mainstream smoke,about 35% of gas phase phenol was found at the tobacco end of the filter,whilst this dropped to approximately 0 at the mouth end of the filter,mostly by selective chemical adsorption.3)The weighted average smoke particle size and particulate phenol was 0.44 and 0.38 pm,respectively.The filtration efficiency of the filter to particulate phenol was near 40%.4)About 19% of particulate bound phenol transferred to gas phase when smoke passing the filter,and was selectively adsorbed.5)The overall filtration efficiency of the CA filter for phenol in mainstream cigarette smoke was 68.7%,with-7.7% variation compared with experimental data.The results demonstrated the phase transition of phenol during the filtration process and the selective retention with varying particle sizes.Our results showed that the application of CA filter in product designs reduces harmful constituents such as phenolic compounds in mainstream cigarette smoke.

尼龙66盐生产中NO_x的治理

辽阳石油化纤公司尼龙生产线硝酸装置ＮＯｘ尾气排放是长期以来难以解决的环境问题，国内外硝酸尾气治理已有许多较成熟的经验．辽化公司采用选择性还原法，将硝酸尾气中ＮＯｘ转化成氮气和水．该工程竣工后，投运一次成功．经监测，尾气中ＮＯｘ含量已由处理前的１２００ｐｐｍ降低到５０ｐｐｍ，环境效益和社会效益极为明显．

A customized zeolitic imidazolate framework enabling bionic preconcentration of ultralow CO_(2)

Advancing our understanding of global climate,particularly in polar regions,requires accurate detection of carbon dioxide(CO_(2))in ice cores and deep sea environments.However,detecting trace levels of CO_(2)in these areas presents significant challenges.We introduce a novel preconcentration approach using functionalized zeolitic imidazolate framework,ZIF-8(CN),for the detection of ultra-low CO_(2).ZIF-8(CN)has small pores(4.4■and cyano groups(–CN),enabling highly selective adsorption of CO_(2)(36.2 cm^(3)g^(−1))over N_(2)(1.6 cm^(3)g^(−1))at 298 K.The mechanism involves unique–CN···CO_(2)···–CN interactions within the pore structure.When cast into a film on an aluminum substrate,ZIF-8(CN)demonstrates exceptional CO_(2)preconcentration capability(1 ppm in N_(2))with an extraordinary preconcentration factor of 748,outperforming traditional ZIF and zeolite materials.Additionally,a ZIF-8(CN)preconcentrator is designed and fabricated with bionic gas flow of fractal structure which optimizes the gas-film contact,and thus its performance is further improved by 115%.

Efficient C_(2) Hydrocarbons and CO_(2) Adsorption and Separation in a Multi-site Functionalized MOF

A multi-site functionalized microporous metal-organic framework(MOF),H[Zn2(BDP)0.5(ATZ)3]·0.5 H_(2)O·0.5DMF(1),was synthesized through mixed ligands strategy.The pore surface of complex 1 was modified by uncoordinated carboxylate O atoms,phenyl and pyridyl rings as well as-NH_(2) groups,which strengthen interactions with C2H6,C_(2)H_(4) and CO_(2) molecules and lead to efficiently selective C2H6,C_(2)H_(4) and CO_(2) uptake over CH_(4).The selective adsorption mechanism was discussed deeply based on Grand Canonical Monte Carlo(GCMC)simulations.It is expected that this study will provide a new perspective for the rational design and synthesis of MOFs with efficient gas adsorption and separation performance.

The influences of composition and pore structure on the adsorption behavior of CH_(4) and CO_(2) on shale

CO_(2) enhanced shale gas recovery(CO_(2)-ESGR)has attracted extensive attention as it can improve the shale gas recovery efficiency and sequestrate CO_(2) simultaneously.In this study,the relationship between mineral composition,pore structure,CH_(4) and CO_(2) adsorption behavior as well as selective adsorption coefficient of CO_(2) over CH_(4)(αCO_(2)/CH_(4))in marine and continental shales at different temperatures was investigated.The results illustrated that shale with higher total organic carbon(TOC),higher clay minerals and lower brittle mineral contents has a larger micropores and mesopores volume and specific surface area.TOC content was positively correlated with fractal dimension Df.Both CH_(4) and CO_(2) adsorption capacity in shale have positive correlations with TOC and clay mineral content.CO_(2) adsorption capacity of the all the tested shale samples were greater than CH_(4),and theαCO_(2)/CH_(4) of shale were larger than 1.00,which indicated that using CO_(2)-ESGR technology to improve the gas recovery is feasible in these shale gas reservoirs.A higher TOC content and in shale corresponding to a lowerαCO_(2)/CH_(4) due to the organic matters show stronger affinity on CH_(4) than that on CO_(2).Shale with a higher brittle mineral content corresponding to a higherαCO_(2)/CH_(4),and no obvious correlation betweenαCO_(2)/CH_(4) and clay mineral content in shale was observed due to the complexity of the clay minerals.TheαCO_(2)/CH_(4) of shale were decreased with increasing temperature for most cases,which indicated that a lower temperature is more favorable for the application of CO_(2)-ESGR technique.