Industrial & Engineering Chemistry Research最新文献

Steam cracking coils are pushed more and more to their limits during the cracking/decoking cycles, going in some cases to metal temperatures beyond 1100 °C. To accurately mimic actual steam cracking conditions within various parts of an industrial coil and to delve deeper into the alloy behavior during the process, we introduce the so-called inductively heated electro-balance setup (IHEB), which allows conducting steam cracking tests on representative coupons produced from actual coils. The IHEB unit utilizes both inductive and radiative heating to independently control coil surface and gas phase temperatures to mimic the conditions endured in each part of a real steam-cracking coil. As a proof of concept, a study is conducted on coupons made of a commercial heat-resistant Ni-based alloy. The steam cracking test protocol is designed so that the coupon undergoes the same treatment as it would in an industrial furnace. Throughout the test, a magnetic suspension balance (MSB) monitors and measures variations in coupon weight in real time. This enables in situ interpretation of catalytic and asymptotic coking rates over multiple coking/decoking cycles. The microstructure and chemical composition of the coupons are analyzed using mainly scanning electron microscopy and energy-dispersive X-ray spectrometry (SEM/EDX), and transmission electron microscopy (TEM). Results show that the treated coupons exhibit similar microstructures to those observed in real industrial cracking coils, demonstrating that the IHEB unit can provide realistic information about the stability or degradation of high-temperature alloys under the influence of the steam cracking process.

This study compares the adsorption and separation performance of Xe/Kr mixtures in realistic and slit pore models of activated carbon using Grand Canonical Ensemble Monte Carlo (GCMC) simulations. The hybrid Reverse Monte Carlo (HRMC) model and slit pore structures exhibit distinct adsorption behaviors influenced by pore size, pressure, and temperature. For pure Xe and Kr, adsorption heats in the HRMC model range from 12 to 20 kJ/mol for Kr and 15 to 25 kJ/mol for Xe. At 1 MPa, cs1000a achieves the highest adsorption capacities for Kr and Xe, 1.93 and 3.84 mmol/g, respectively. In slit pores, the Xe/Kr selectivity peaks at 32 for 0.8 nm pores at 0.1 MPa and decreases with pressure and pore size. The 1.1 nm slit pore at 1.0 MPa and 238 K achieves a maximum Xe adsorption capacity and selectivity of 14. Local density analyses confirm selective Xe adsorption in narrow pores, with enhanced multilayer adsorption in larger pores. Compared to the HRMC model, slit pores exhibit higher adsorption heat and steeper isotherms, indicating stronger interactions. This study highlights the importance of pore structure in designing activated carbons for Xe/Kr separation, recommending operating conditions of 1.1 nm pore width, 238 K, and 1.0 MPa for optimal separation performance.

A sustainable, template-free self-assembly synthesis was used to fabricate biomass-based, highly efficient HPCFs@FeCoNi@NC (HPCFs refer to helical/chiral porous carbon fibers at 700 and 800 °C carbonization temperatures, and NC is accredited to N-doped porous carbon structures) as electromagnetic wave absorbers (EMAs). The synthesis of HPCFs@FeCoNi@NC as an EMA circumvents prerequisite tiresome treatments, laborious work, high energy-intensive chemical fabrication, and precursors (e.g., MOF-74) and other organic binders (PVA, PVB, H₄DOT, etc.). The fabricated EMA exhibits top-notch electromagnetic wave (EMW) absorption capabilities with improved reflection loss (RL) across a broad spectrum, achieving efficient absorption bandwidth (EAB, RL ≤ −10 dB), covering 0.90–7.00 GHz over 3.00–18.00 GHz at a 1.00–6.00 mm matching thickness. Noticeably, HPCFs₇₀₀@FeCoNi@NC_2b as an EMA has gained an RL of −86.16 dB over 11.60 GHz, with the EAB covering 9.60–13.80 GHz (4.20 GHz) at a matching thickness of 2.60 mm. Furthermore, HPCFs₈₀₀@FeCoNi@NC_2b achieved an RL of −86.28 dB with an EAB of 2.20 GHz (covering 8.70–10.90 GHz) at a 2.44 mm matching thickness and 9.60 GHz. The EMA’s improved RL over a broad-spectrum EAB is accredited to its unique structural morphology, better dissipation/attenuation mechanisms of EMW, additional loss mechanisms, and so on. Likewise, the EMA’s ability to dissipate/attenuate EMW across low and high frequencies (3.00–18.00 GHz) makes it a novel contender for futuristic applications.

Selective photoreduction of carbon dioxide (CO₂) to methane (CH₄) remains a major challenge, which involves a kinetically unfavorable transfer of eight protons and eight electrons. Herein, a photodeposition strategy was employed to deposit nano Cu metal on flower-like Nb₂O₅ microspheres (Cu/Nb₂O₅) for CO₂ photoreduction to generate CH₄ under simulated sunlight. The results show that the 1.0% Cu/Nb₂O₅ catalyst produces CH₄ with an electron selectivity of 84.8% and a formation rate of 15.89 μmol g^–1 h^–1 without the use of sacrificial agents and photosensitizers. The generation of *CH₃O on the 1.0% Cu/Nb₂O₅ catalyst during the CO₂ photoreduction process was monitored using in situ Fourier transform infrared spectroscopy. Theoretical calculations further indicate the formation of highly stable C1 intermediates plays a crucial role in determining the reaction selectivity. By optimizing the electronic structure of the catalyst, this strategy provides a viable strategy for the photocatalytic conversion of CO₂ and H₂O into CH₄ products, offering new insights into the development of efficient and sustainable CO₂ conversion technologies. Moreover, it provides strong theoretical support and an experimental basis for the widespread application of photocatalytic CO₂ reduction in greenhouse gas emission reduction and green energy production.