Buton rock asphalt (RA) majority composed of a mixture of calcite and petroleum-like material that is abundantly available in Buton, Indonesia. Direct pyrolysis of RA reveals the catalytic role of calcite in efficiently transforming the fused aromatic rings of asphaltene in RA into diesel-range hydrocarbons. Pyrolysis at 400 degrees C for 180 min produced a 74% liquid product yield, significantly higher than that obtained from pyrolysis of decalcified RA (22.9%), or decalcified RA using commercial CaCO3 (34.2%). The resulting liquid hydrocarbon contains 70.30% diesel fraction, 25.72% heavy oil, and 3.98% gasoline, and exhibits a higher cetane number (69) than commercial diesel fuel. These findings highlight the importance of strong calcite/asphaltene interactions for efficient heat transfer during hydro-dearomatization of aromatic rings. Furthermore, the high thermal stability and strong basicity of calcite catalyze the cracking process into diesel-range hydrocarbons. This study offers a roadmap for the efficient conversion of low-quality Buton rock asphalt into high-quality diesel fuel through direct pyrolysis at 400 degrees C.
PurposeThis study aims to examine how the relationship between managerial ties (i.e. business ties, political ties and university/research institution ties) and firm performance is mediated by external resource acquisition, comprising tangible external resource acquisition (TERA) and intangible external resource acquisition (IERA). It further considers the boundary conditions imposed by competitive intensity and resource orchestration capability (ROC).Design/methodology/approachA two-round, time-lagged survey was conducted among 543 middle- and top-level managers from business-to-business (B2B) manufacturing firms in Nigeria and the data were analyzed using partial least squares structural equation modeling.FindingsThe results reveal that business ties, political ties and university/research institution ties positively enhance firm performance. Furthermore, TERA mediates the effect of the three forms of managerial ties on firm performance. In addition, IERA mediates the effect of business ties and university/research institution ties on firm performance. Competitive intensity moderates the effects of business ties and university/research institution ties on TERA, as well as the effects of political ties and university/research institution ties on IERA. Finally, ROC moderates the effect of IERA on firm performance.Originality/valueAlthough prior studies have considered the role of managerial ties (excluding university/research institution ties) in driving firm performance, the mediating effects of TERA and IERA have been largely overlooked, particularly within the B2B firms operating in resource-constrained contexts. Additionally, the inclusion of competitive intensity and ROC as boundary conditions in the proposed framework represents another novel contribution to knowledge.
PurposeManufacturing firms face increasing stakeholder pressure to optimize business processes, improve waste management and enhance sustainable performance (SP). Achieving these objectives requires the strategic implementation of green initiatives, sustainable practices and digitalization. Given this, the study investigates how green entrepreneurial orientation (GEO) influences SP through the mediating role of circular economy practices (CEPs) and the moderating role of digital capability (DC).Design/methodology/approachData were collected using a two-wave time-lagged field survey from 543 manufacturing MSMEs in Nigeria. Partial least squares structural equation modeling (PLS-SEM) was conducted using SmartPLS 4 to analyze the data.FindingsThe results indicate that GEO has a positive and significant effect on both CEP and SP. Furthermore, CEP partially mediates the relationship between GEO and SP, suggesting that the influence of GEO on SP also operates indirectly through CEP. In addition, the results show that DC significantly moderates the relationship between GEO and CEP, while its moderating effect on the GEO-SP relationship is not significant.Originality/valueThis study is among the first to empirically examine the interconnected relationships among GEO, CEP, DC and SP through the lens of dynamic capabilities theory. It also provides actionable insights for manufacturing MSMEs on formulating policies and strategies that strengthen CEP and, in turn, enhance SP.
Up to date, the development of highly efficient, visible light-active catalysts remains a formidable challenge due to the enhanced rising of atmospheric CO2 concentration. This study discusses a class of ceria-based high-entropy oxides designed to optimize charge carrier dynamics, surface reactivity, and CO2 activation efficiency. Due to the advantages of high configurational entropy and multi-element synergy, these materials achieved improved photocatalytic performance, surpassing conventional ceria-based systems. Structural and spectroscopic analyses reveal that Pr3+/Pr4+ redox pairs and abundant oxygen vacancies create an electronically disordered yet thermodynamically stable environment, which enhances charge separation and suppresses electron-hole recombination. Photocatalytic experiments demonstrated that Ce0.2Zr0.2La0.2Pr0.2Sm0.2O2-delta (CZLPS) achieves the highest CO2 conversion rate, reaching a conversion of 20.3% under visible light irradiation, significantly surpassing pure ceria (1.4%), with a calculated space-time yield (STY) of 10.15 mol(CO)kg(-1)h(-1) under the same conditions. First-principles density functional theory (DFT) simulations were employed to investigate the CO2 reduction mechanism on CZLPS catalysts. The study elucidates the Gibbs free energy changes (Delta G) for each step of the reaction pathways leading to CO and HCOOH formation, highlighting the Zr site of CZLPS as the most active for the CO2RR, which is responsible for the outstanding catalytic activity
Titanium dioxide (TiO2) is extensively implemented in photocatalytic hydrogen (H2) production. However, the rapid recombination rate of photogenerated electron–hole pairs in TiO2 limits the potential to catalyze H2 photogeneration. In this study, we rationally designed nickel/nickel selenide@nitrogen-doped carbon/TiO2 (Ni/NiSex@NC/TiO2) heterostructures via impregnation assisted by ultrasonication to enhance the photocatalytic activity of TiO2 in H2 production. This strategy yields a high interfacial contact between TiO2 and Ni/NiSex@NC, which reduces the band gap energy and enhances the surface area. This combination yields a type-II heterojunction, as evidenced by X-ray photoelectron spectroscopy analysis of used Ni/NiSex@NC/TiO2 and OH radical trapping via fluorescence analysis, with high conductive features due to the presence of NC. The presence of Ni metal provides additional sites for H2 photogeneration. Such features significantly enhance the transfer and separation of electrons, as evidenced by a series of electrochemical analyses. Consequently, the photocatalytic H2 generation of Ni/NiSex@NC/TiO2 nanocomposites is enhanced compared with TiO2, NiSe/TiO2, and Ni/NiSex@NC. Moreover, the highest H2 production rate is achieved by incorporating 3 wt
