Heavy oil millisecond gas-phase in-line catalytic dehydrogenation over bifunctional catalysts was adopted to produce low-carbon olefins. In this study, the effect of the uncatalyzed reaction composition and distribution of atmosphere residue (AR) pyrolysis vapor at 650 degrees C was investigated for the first time. In the pyrolysis vapor, the yield of low-carbon olefins was only 15.2%. The yield of 1-olefin and n-alkanes, which are the primary products of rapid heavy oil pyrolysis, reached approximately 54.0%. To achieve further catalytic dehydrogenation, AR pyrolysis volatiles were catalyzed over single calcium aluminate (C(12)A(7)), ZSM-5, and C(12)A(7)-ZSM-5 (CZ) catalysts at 650 degrees C, which possess different pore structures, and acid-base properties. The ZSM-5 catalyst obtained the highest low-carbon olefin yield after catalytic dehydrogenation of pyrolysis volatiles. Finally, the C(12)A(7 )and CZ stepwise coupling bifunctional catalysts increased the catalytic activity, and thus increased the higher low-carbon olefin yield but reduced the yields of alkanes and aromatics fraction. Notably, the yields of propylene and butane were important sources of the low-carbon olefins. Thus, heavy oil millisecond gas-phase in-line catalytic dehydrogenation could achieve the maximum conversion of these residues to produce low-carbon olefins.
By evaluating the SEM images,specific surface area,and the catalytic synthesis reaction conditions of an activated carbon-supported p-toluenesulfonic acid catalyst,and comparing the physical and chemical properties,infrared spectra,nuclear magnetic resonance spectra,oxidation stability,thermal stability,hydrolytic stability,and extreme pressure anti-wear performance of the synthesized trihydroxymethylpropyl trioleate with imported reference esters,the feasibility of its application as a substitute was investigated.The results indicated that the activated carbon-supported p-toluenesulfonic acid catalyst exhibited loose porosity,high specific surface area,and high esterification efficiency.When synthesized under optimal conditions,the yield rate of trihydroxymethylpropyl trioleate reached 99.3％,with a simple separation process that did not require additional steps such as neutralization and washing and generated minimal wastewater.The physical and chemical properties of the synthesized trihydroxymethylpropyl trioleate were comparable to those of the reference ester in terms of color,viscosity,viscosity index,flash point,and pour point.Moreover,the peak position and peak height in the infrared and nuclear magnetic carbon spectra were essentially the same.Through comprehensive evaluations and comparisons of various properties,it was determined that the performance of trihydroxymethylpropyl trioleate was comparable to that of the imported reference esters.
Due to increasingly stricter emissions on particulate matter(PM)emissions,diesel particulate filter(DPF)regeneration has become the most widely used and effective technology to reduce PM emissions.However,using in-cylinder post-injection-based active DPF regeneration can increase engine oil dilution,thus affecting engine lubrication.Using a 4-cylinder turbocharged direct-injection diesel engine,this study analyzed the effect of lubricating oil on the formation and properties of turbocharger compressor soot deposits associated with engine oil dilution.Three diesel engine lubricating oils(CJ-4,CK-4,and CJ-4*)were selected,with each subjected to 200 hours of engine bench testing at 8％oil dilution.The composition of CJ-4* was the same as that of CJ-4 but with reduced amount of additives.Soot deposits were collected and analyzed.A merit calculation method was established to rate turbocharger deposits.Transmission electron microscopy,Raman spectroscopy,Fourier transform infrared spectroscopy,and thermogravimetric analysis(TGA)were used to characterize the morphology and composition of soot samples.The results showed that turbocharger deposits from CJ-4 and CK-4 were less than that from CJ-4*.The deposits from CJ-4* showed a more disordered morphology,whereas those from CJ-4 and CK-4 exhibited a higher degree of order.TGA results showed that the soluble organic fraction content in the deposit derived from CJ-4*was much higher than that obtained from CJ-4 and CK-4.
Fe-Al catalysts with hollow nano-spherical structures were synthesized following the hard template method using self-made carbon spheres as templates.The catalytic performance of these catalysts in the production of carbon nanotubes(CNTs)was evaluated through ethane catalytic cracking on a fixed bed reactor.Furthermore,the influence of these hollow nanospheres on the yield and quality of CNTs was investigated.The results showed that compared to the irregular-shaped catalyst synthesized by coprecipitation and the catalyst with micro-spherical structures prepared by the impregnation method,the Fe-Al hollow nano-spherical catalysts exhibited significantly enhanced specific surface area and pore volume,reaching 236 m2/g and 0.77 cm3/g,respectively.At a reaction temperature of 700 ℃ and an ethane feed rate of 90 mL/min,the CNTs yield of Fe-Al hollow nano-spherical catalyst reached as high as 48.6 gCNT/gcat,which was 1.8 and 4.6 times higher than the yield of irregular-shaped(27.7 gCNT/gcat)and micro-spherical(10.5 gCNT/gcat)catalysts,respectively.This was mainly attributed to the hollow cavity structure of Fe-Al catalyst providing sufficient space for the CNTs growth.As a result,the blockage of catalyst internal pores was prevented by the formed CNTs,which isolated ethane molecules from the active sites and lead to catalyst deactivation.Furthermore,the CNTs synthesized by Fe-Al hollow nano-spherical catalyst exhibited a uniform diameter distribution and a higher degree of graphitization.
This study investigates the simultaneous accumulation of S-0 and NO2- during short-cut sulfur autotrophic denitrification (SSADN) in response to 0-35 mg/L hydroxylamine (NH2OH) addition. At a dosage of 15 mg/L NH2OH, the accumulation of NO2--N peaked at 32.49 +/- 1.33 mg/L, which is 1.65 times higher than that of the control. The addition of NH2OH facilitates the retention of S-0 in the system. Enzyme assays indicated significant discrepancies in the enhanced NO3--N reductase (NAR) and NO2--N reductase (NIR) activities induced by NH2OH are responsible for the excellent NO2--N production. These results are supported by the corresponding NO3--N reduction genes (napA, narG) and NO2--N reduction genes (nirS, nirK). In addition, the abundance of sulfur oxidation genes (soxB) decreases with increasing NH2OH dosage, inhibiting further oxidation of S-0 to SO42-. The accumulation of NO2---N and S-0 increases from 45.8% and 36.8% to 70.04% and 52.52%, respectively, with the addition of 2 mg/L NH2OH in the continuous-flow up-flow anaerobic sludge blanket (UASB) reactor.
