Target Product Research Articles

Pot-Economical Approaches to the Synthesis and Functionalization of Phthalocyanines for Clean Energy Production

The last decades have witnessed a growing interest in reducing the ecological and economic impact of chemical processes, with an important focus on the development of more environmentally friendly procedures and methodologies in organic synthesis. Given the extreme versatility and technological importance of phthalocyanines for a variety of applications, of which clean energy production is among the most relevant, the design and study of alternative and less-impacting synthetic approaches to the conventional ones have gained importance in the last years. Their synthesis in solution frequently requires reaction media such as high boiling point alcohols (pentanol, hexanol), dimethylaminoethanol, chlorobenzene, quinoline, and α-chloronaphthalene, most of which are toxic and non-environmentally friendly. Some green synthetic approaches based on solvothermal methods [1,2], mechanochemistry [3], or alternative sources of energy such as microwaves [4-6] and ultraviolet radiation [7], have been developed in order to minimize if not overcome this issue and provide less-impacting experimental conditions for their production. A less studied but very promising approach concerns the development of pot-economical processes, in which two or more reactions take place in the same reaction vessel. The advantage of this approach is twofold: on the one hand it significantly reduces the amount of chemicals required to synthesize and purify a target product, on the other it minimizes the total time required to obtain it. Clearly, the process must be carefully designed in order to avoid yield decreases due to side reactions.In this contribution, the rational design of symmetrical and unsymmetrical substituted phthalocyanines by means of pot-economical approaches in solution will be shown and discussed, along with an estimation of the environmental and economic impact with respect to the related conventional procedures. Examples will be shown both of derivatization of already formed macrocycles, following a “late-stage functionalization” approach [8], and of derivatization of phthalonitriles followed by in-situ metal-templated cyclotetramerization. Furthermore, their optical and electrochemical characterization will be shown, discussed and compared with each other by relating the obtained data to their different chemical structures. Finally, examples of their implementation in the field of organic optoelectronics, with a focus on perovskite solar cells, will be presented. D. Li et al CrystEngComm 2018, 20, 2749–2758.D. Li, et al RSC Adv. 2021, 11, 31226–31234.D. Langerreiter et al Angew. Chem. Int. Ed. 2022, 61, e202209033.A. Shaabani et al Dyes Pigm. 2007, 74, 279–282.D. Villemin et al Molecules 2001, 6, 831–844.A.C.S. Gonzalez et al. J. Porphyr. Phthalocyanines 2020, 24, 947–958.Y. Saito et al Chem-NanoMat 2015, 1, 92–95.G. Zanotti et al ChemPlusChem 2020, 85, 1–12

Syntheses of Heteroatom-Substituted and Three-Dimensional Nanocarbon Materials on Surfaces

I will present our recent studies on on-surface chemistry with high-resolution scanning probe microscopy operating at low temperature under ultra-high vacuum. We synthesized three-dimensional organometallic compound and graphene nanoribbon by coupling hexabromo substituted-propellane molecules on Au(111) and Ag(111).[1] In the structure, the C-Br bonds distant from the surface remained intact even after the reaction. The radical species were formed by tip-induced debromination and were also stabilized by either tip-manipulated Br atom or fullerene molecule. We also demonstrate systematic tip-induced isomerization via embedding a text of “NIMS” by following binary and ternary ascii cords, in which two chiral dehydroazulene and diradical units were used.[2] Among the three states, the diradical unit showed the spin coupling of 90 meV. For heteroatom substitution, we developed an on-surface reaction, which can synthesize graphene nanoribbon and covalent organic frameworks with silabenzene units by coupling Si atom and Br-substituted molecule.[3] The heavier congeners of cyclic aromatic compounds have been studied as an elusive target product for organic synthesis due to their high reactivity at ambient temperature and difficult isolation. Thus, this result shows the advantage of on-surface synthesis.Reference[1] S. Kawai, et al Sci. Adv. 6, eaay8913 (2020).[2] S. Kawai, et al Nat. Commun. 14, 7741 (2023).[3] K. Sun et al, Nat. Chem. 15, 136 (2023).

(Invited) Techno-Economics of Photoelectrochemical Water Splitting and Progress in Cost Reduction of High-Efficiency III-V Photoabsorbers

Photoelectrochemical (PEC) water splitting is a potentially promising route to direct solar-driven hydrogen production. Challenging targets for solar-to-hydrogen (STH) efficiency, durability, and semiconductor absorber costs must be realized for this approach to be economically competitive with other hydrogen production pathways. The first part of this talk will focus on the cost and performance metrics that go into techno-economic analysis and their status.Research on PEC hydrogen production at the National Renewable Energy Laboratory (NREL) has focused on III-V semiconductor absorber materials because their tunable bandgaps, high photon conversion efficiencies, and ability to make multi-junction structures that have resulted in the highest STH efficiencies yet demonstrated. However, to achieve the U.S. DOE’s hydrogen production target of $2/kg, in addition to high STH efficiency, the semiconductor absorber synthesis cost must come down 1-2 orders of magnitude from the current metal organic vapor phase epitaxial route. Hydride vapor phase epitaxy (HVPE) is a technique that has the potential to lower tandem III-V synthesis costs. The second part of this talk will describe experimental photoelectrochemical characterizations of HVPE-grown GaInP/GaAs tandem photoelectrodes with 1.85/1.38 eV bandgaps. Their incident photon-to-current efficiency, photocurrent vs. circuit bias, and unbiased chronoamperometry will be presented and discussed. Upon illumination, the HVPE-grown structures were able to drive water electrolysis spontaneously (e.g., without an external bias) at STH efficiencies up to 10%. The durability of III-V photoelectrodes remains an unresolved challenge for cost effective hydrogen production via photoelectrolysis.

Paving the way for low-carbon hydrogen supply chain deployment by exploring the potential of renewable energies and multisectoral hydrogen demand: Case study of France

France has set ambitious targets for hydrogen production in its National Roadmap, aiming to install at least 6.5 GW of electrolyzer capacity and produce 700,000 tons of hydrogen annually by 2030. The country is focusing on producing renewable or low-carbon hydrogen primarily through electrolysis. However, it faces significant barriers in rapidly scaling up renewable energy infrastructure and may need to consider import strategies to address potential shortages. Addressing these challenges requires investigating whether the availability of renewable energy for the production of electrolytic hydrogen could become a limiting factor for hydrogen adoption and potentially act as a bottleneck in its market integration. The methodology merges forecasts from the public and private sectors to address both renewable and non-renewable electricity production and the energy needed for rising hydrogen demand. The approach developed involves estimating France’s renewable energy supply up to 2050 and determines how much of this energy can be allocated to hydrogen production to ensure it remains carbon-free and genuinely renewable. Unlike many existing roadmaps that take a more general approach, the innovative part of this study is developing a territorial perspective to conduct a detailed analysis of potential mismatches between hydrogen supply and demand.Three distinct sources of electricity are considered for the electrolyzers, which could be connected to the grid or directly to renewable power plants: low-carbon electricity from the French grid, renewable electricity from re-powered solar and wind farms, and renewable electricity from newly installed power plants. Total electricity demand is projected to rise from 475 TWh/y in 2020 to 754 TWh/y in 2050, with the share of renewable energy increasing from 19% in 2020 to 69% in 2050.The study evaluates the demand for hydrogen in two key sectors, industry, which is heavily dependent on hydrogen, and mobility, which currently has a more modest contribution. Hydrogen demand is expected to increase from nearly 310 ktons per day in 2025 to over 2650 ktons per day by 2050.Given an average specific consumption of 55 kWh of electricity per kg of hydrogen produced, the total electricity demand for electrolytic hydrogen production is projected to grow from 17 TWh/year in 2025 to 146 TWh/year in 2050.It can be concluded that allocating the entire anticipated production from re-powered solar and on-shore wind farms in the coming years will not be sufficient to meet the electricity demand required for electrolytic hydrogen production. To prevent renewable energy from becoming a bottleneck for hydrogen market integration and to avoid the need for hydrogen imports, it is crucial to allocate 5% to 10% of the projected renewable output from newly installed plants to address the increasing hydrogen demand. This result is key to creating an optimal design model for hydrogen supply chains.

Optimizing Nitrate Reduction to Ammonia via Modulating Adsorption-Desorption Dynamics with High-Entropy CuNiCoZnMn Alloy Catalysts.

NO3RR synthesis of ammonia is a complex eight-electron reaction involving multiple steps and intermediates, in which NO3- adsorption and NH3 desorption are crucial. The Cu-based high entropy quinary alloy catalyst has good surface adsorption and desorption ability for the reduction of nitric acid to ammonia. Here, the catalytic sites were coordinated by constructing CuNiCoZnMn alloys to adjust the electronic structure of the catalytic sites to facilitate the reaction of the substrate and thus optimize the whole reaction path. Based on the ternary alloy CuNiCo, the introduction of the Zn element continues to reduce the desorption energy barrier, and the introduction of the Mn element continues to enhance the initial adsorption energy so that the target product can be quickly held and released to accelerate the production of ammonia. The NH3 yield and Faraday efficiency obtained for the quinary CuNiCoZnMn alloy catalyst reached 723.7 μmol h-1 cm-2 and 96.6%, respectively, at -0.35 V vs RHE potential. The density functional theory calculations showed that the quinary CuNiCoZnMn alloy (NO3- to *NO3-) initial adsorption-free energy change and (*NH3 to NH3) NH3 desorption-free energy change are -2.50, 0.072 eV, respectively, which are significantly better than those of the ternary CuNiC and quaternary CuNiCoZn of -2.02, 0.544 eV and -1.97, 0.217 eV.

Carbon Nanodots: An Illuminating Paradigm in Production, Characterization, and Oncological Targeting Methodologies—A Review

Carbon Nanodots: An Illuminating Paradigm in Production, Characterization, and Oncological Targeting Methodologies—A Review

Effect of pyrolysis operating conditions on the catalytic co‐pyrolysis of low‐density polyethylene and polyethylene terephthalate with zeolite catalysts

AbstractIn this study, the catalytic (co‐)pyrolysis of low‐density polyethylene (LDPE) and polyethylene terephthalate (PET) with HZSM‐5 and HY zeolite catalysts was conducted in a micro‐pyrolysis reactor coupled to a two‐dimensional gas chromatography system. Pyrolysis operating conditions, such as the pyrolysis temperature, the catalyst to feedstock (CF) ratio, and the LDPE:PET ratio, were varied. It was found that for the co‐pyrolysis of LDPE and PET, HZSM‐5 led to higher yields of C2‐C4 olefins and monoaromatic products. Lower CF ratios increased the yield of C2‐C4 olefins for LDPE pyrolysis, but decreased benzene yield for PET pyrolysis, concomitant with an increased yield in benzoic acid. A lower temperature of 400°C which was sufficient for the pyrolysis of LDPE, led to incomplete conversion of PET. Surface response diagrams were used to visualize the impact of the various pyrolysis operating conditions on the yield of C2‐C4 olefins and BTEX, which serve as target products for the circular economy.

A Photoenzymatic Pathway for Gram-Scale Synthesis of 25-Hydroxyvitamin D3.

Vitamin D and its analogues play a crucial role in promoting the well-being of both humans and animals. However, the current synthesis of this vital class of nutrients heavily relies on chemical transformations, which suffer from low step- and atom-efficiency due to lengthy synthetic pathways. To enhance sustainability in the chemical industry, it is necessary to develop alternative synthetic processes. Herein, we present a photoenzymatic approach for synthesizing 25-hydroxyvitamin D3 from 7-dehydrocholesterol. In this sequential synthesis, 7-dehydrocholesterol is initially hydroxylated at the C25 C-H bond, resulting in an 85 % conversion to 25-hydroxyl-7-dehydrocholesterol. Subsequently, by employing photo-irradiation using a monochromatic LED ultraviolet light source in a batch reactor and thermal isomerization, 25-hydroxyvitamin D3 is obtained in satisfactory yield. This photoenzymatic process significantly reduces the need for purification steps and allows for gram-scale synthesis of the target product. Our work offers a selective, efficient, and environmentally friendly method for synthesizing 25-OH-vitamin D3, addressing the limitations of current synthetic approaches.

Quantitative drug susceptibility testing for Mycobacterium tuberculosis using unassembled sequencing data and machine learning.

There remains a clinical need for better approaches to rapid drug susceptibility testing in view of the increasing burden of multidrug resistant tuberculosis. Binary susceptibility phenotypes only capture changes in minimum inhibitory concentration when these cross the critical concentration, even though other changes may be clinically relevant. We developed a machine learning system to predict minimum inhibitory concentration from unassembled whole-genome sequencing data for 13 anti-tuberculosis drugs. We trained, validated and tested the system on 10,859 isolates from the CRyPTIC dataset. Essential agreement rates (predicted MIC within one doubling dilution of observed MIC) were above 92% for first-line drugs, 91% for fluoroquinolones and aminoglycosides, and 90% for new and repurposed drugs, albeit with a significant drop in performance for the very few phenotypically resistant isolates in the latter group. To further validate the model in the absence of external MIC datasets, we predicted MIC and converted values to binary for an external set of 15,239 isolates with binary phenotypes, and compare their performance against a previously validated mutation catalogue, the expected performance of existing molecular assays, and World Health Organization Target Product Profiles. The sensitivity of the model on the external dataset was greater than 90% for all drugs except ethionamide, clofazimine and linezolid. Specificity was greater than 95% for all drugs except ethambutol, ethionamide, bedaquiline, delamanid and clofazimine. The proposed system can provide quantitative susceptibility phenotyping to help guide antimicrobial therapy, although further data collection and validation are required before machine learning can be used clinically for all drugs.

Harnessing artificial intelligence microscopy to improve diagnostics for soil-transmitted helminthiasis and schistosomiasis: a review of recent advances and future pathways.

This opinion piece aims to explore the transformative potential of integrating artificial intelligence with digital microscopy to enhance diagnostics for soil-transmitted helminthiasis (STH) and schistosomiasis (SCH), two pervasive neglected tropical diseases (NTDs). By aligning innovative artificial intelligence-driven solutions with WHO's strategic objectives and calls for better, more accessible, and more integrated diagnostics, we highlight the latest advancements that may support improved health outcomes in affected communities. The review covers recent advancements in artificial intelligence-based diagnostic technologies, emphasizing automated egg detection and quantification. These technologies promise to mitigate challenges such as human error and the need for skilled technicians. The findings have significant implications for public health, ethical considerations and regulatory pathways, particularly in resource-limited settings. The authors advocate for interdisciplinary collaboration and a strategic focus on meeting WHO target product profiles to ensure uptake, ultimately to support reaching WHO NTD targets.

Quality by Design in Pulmonary Drug Delivery: A Review on Dry Powder Inhaler Development, Nanotherapy Approaches, and Regulatory Considerations.

Dry powder inhalers (DPIs) are state-of-the-art pulmonary drug delivery systems. This article explores the transformative impact of nanotechnology on DPIs, emphasizing the Quality Target Product Profile (QTPP) with a focus on aerodynamic performance and particle characteristics. It navigates global regulatory frameworks, underscoring the need for safety and efficacy standards. Additionally, it highlights the emerging field of nanoparticulate dry powder inhalers, showcasing their potential to enhance targeted drug delivery in respiratory medicine. This concise overview is a valuable resource for researchers, physicians, and pharmaceutical developers, providing insights into the development and commercialization of advanced inhalation systems.

Petrochemical Industry for the Future

Petroleum has played a vital role as the major supplier of materials and energy during the evolution of human civilization. Given the change in demand for energy from high to low carbon and ultimately net zero carbon, the energy framework has undergone revolutionary changes. The energy attribute of petroleum will be gradually weakened, while the material and CO2 emission attributes will be gradually strengthened. Thus, the petrochemical processing basis, scientific concepts, and ideas will undergo major adjustments to reshape the petrochemical industry. Hence, it is necessary to reconsider the evolution of the petrochemical industry from a historical perspective and to clarify the historical causes, development contexts, and possible challenges in future development. Herein, we critically reassess the key drivers and rules guiding the development of the petrochemical industry and propose a reconstruction strategy based on simplified engineering thinking, innate nature of energy and material, and CO2 emissions, which can be realized through the integration of gasification with CO as the target product and recent C1 chemistry targeting the precise synthesis of chemicals. The concept of the petrochemical industry will change from the product-based process of selection and transformation of raw material molecules to the process of carbon atom reconfiguration driven by product CO2 emissions. More accurate management of C atoms can be accomplished with greatly improved utilization efficiency and the reduction of separation intensity and CO2 emissions via the stepwise introduction of a new approach in the current petrochemical industry.

IMPLEMENTATION OF INTEGER PROGRAMMING USING THE BRANCH AND BOUND METHOD ASSISTED BY PYTHON IN OPTIMIZING THE PRODUCTION OF COOKIES

Many people are interested in cookies. Due to the high consumer interest in cookies, many companies produce cookies with various variants, one of which is Rizky Bakery. The problem faced by Rizky Bakery is how to determine the amount of production of 6 types of cookies to reach the maximum profit. Rizky Bakery carries out production activities to meet high market demand and standard demand. This study constructs a model that accommodates both conditions. The model is solved by using the Branch and Bound method constraints on materials, manufacturing time, fee labor, payment for resellers, and production targets. The purpose of this research is to determine the total number program model and the optimal solution by maximizing the profit of cookie production using Branch and Bound. Optimization using the Branch and Bound method can utilize the Python programming language with a limit of 50 iterations. Data collection methods used for this research are interviews and documentation. The limitation of the problem in this research is that the model to be studied is limited to the average condition of demand is standard and when demand is high. The results of the analysis at times of high demand showed that the production of nastar cookies, castangel cookies, mawar cookies, putri salju cookies, peanut cookies, and custard cookies in 300-gram packaging respectively are 250, 45, 80, 39, 90, 150 and in 500-gram packages are 40, 10, 10, 6, 45, and 45. While, the result of standard demand in 300-gram packaging respectively are 100, 25, 50, 16, 50, 60 and the 500-gram packaging respectively are 10, 3, 10, 2, 10, 20. The profit earned when the demand is high is IDR 8,769,412.00 and the standard demand is IDR 3,769,504.00.

Viewpoint of multi-omics potential in tuberculosis research: identifying biomarkers for biomanufacturing of efficient control tools

Tuberculosis (TB), caused by Mycobacterium tuberculosis complex (MTBC), remains a global health burden, claiming millions of lives annually. Despite the availability of a vaccine (the Bacillus Calmette-Guérin; BCG), diagnostics (smear microscopy and DNA-based diagnostics) and drugs for treatment, challenges like drug resistance, lower diagnostic sensitivity such as microscopy, instrumentation and high-level operational expertise requirement and poor vaccine efficacy pose a greater hinderance to TB monitoring and control. The inability of the BCG vaccine to protect against TB other than disseminated disease in neonates call for innovative approaches to provide improved interventions. This review highlights the potential of multi-omics as a powerful emerging tool offering a holistic insight into the intricate interplay between pathogens and the host immune response. It discusses the potential of multi-omics for discovering biomarkers as targets for rational drug design, production of more effective vaccines and as stable targets for production of universally applicable rapid diagnostics for early and accurate TB detection as well as monitoring treatment.

A value chain and SWOT analysis for optimizing the self-sufficiency of fish feed to strengthen freshwater aquaculture production in Indonesia

This study evaluates the aquafeed self-sufficiency sector in Indonesia, aiming to provide policy recommendations for optimizing freshwater aquaculture production. The study engaged 1005 participants, including 204 self-sufficient aquafeed producers and 801 fish farmers, covering 88% of the regions where the Ministry of Marine Affairs and Fisheries promotes aquafeed self-sufficiency, conducted in 30 Indonesian provinces. The majority of on-farm and small-scale feed manufacturers continue to operate successfully (91%), with a minor portion discontinuing (9%). Aquafeed products incorporating local ingredients prove cost-effective and receive high acceptance among fish farmers. The sustainability of the aquafeed self-sufficiency sector is closely linked to local ingredient availability, operational aquafeed manufacturing plants, product quality, human resource capabilities, and government policies. The study presents policy recommendations to address these issues, encompassing measures such as ensuring ingredient supply sustainability, providing a mobile laboratory for ingredient and feed analysis, enhancing human resource quality through training, facilitating easier access to financial support, and strengthening central-local government coordination to optimize the aquafeed self-sufficiency program. The rise of the national fish production target from freshwater aquaculture has attracted great attention in the improvement of the aquafeed sector since the sustainability of aquafeed supply is the main driver for the success of aquaculture production.

“Guidance but not the ultimate commandment”: Pros and Cons of Using Pivot Templates in the Audio Description Production Workflow

The need for audio-described audiovisual content is mainly growing due to statutory accessibility required in many countries. Regrettably, despite the popular and legal demand for audio description, broadcasters and producers perceive audio description (AD) as an expensive service with little profit potential. Audio Description Translation (ADT) is an alternative production model that can reduce the time and costs involved in AD production while maintaining quality and increasing the availability of audio-described content in multiple languages. Drawing on a widespread practice of using (pivot) templates in modern subtitling workflows, this article investigates the use of pivot templates in audio description, focusing on the advantages and disadvantages of this production model as perceived by audio description translators. Data was collected in an experiment where six participants, five subtitlers, and an audio describer were asked to translate audio descriptions for Spanish films into Polish via an English pivot template. Results based on the thematic analysis of post-task interviews identify two main advantages: (1) personal advantages for the professionals performing the task and (2) external advantages that can benefit, for example, the production workflow, product, and target audience. The personal advantages are reduced time, effort, and responsibility. The external advantages are enhanced script quality and consistency.

Combinatory effects of pineapple peel liquid organic fertilizer and rice husk charcoal on melon (Cucumis melo L.) growth and yield

The intensive use of synthetic fertilizers in melon cultivation can reduce soil organic matter and fertility, ultimately decreasing productivity. This situation necessitates the improvement of growing media to achieve production targets through the use of rice husk charcoal and liquid organic fertilizer (LOF) from pineapple peel. This study aims to determine the combinatory effects of pineapple peel LOF and rice husk charcoal media on the growth and yield of melon plants. The research employed a factorial randomized block design (RBD) with 6 treatment levels, and data were analyzed using ANOVA followed by an HSD test at the 5% significance level. The results showed an interaction between pineapple peel POC and rice husk charcoal media on the number of leaves variable. The P0M1 treatment (NPK 16:16:16 at 3 g and 50% rice husk charcoal & 50% soil) at 52 days after planting (DAP) produced the highest number of leaves, totaling 26.12. However, this increase in leaf number was not accompanied by an increase in fruit weight or brix levels. These findings open opportunities for further research to understand why the increase in leaf number did not translate to higher fruit weight or Brix levels, and to identify treatment combinations that can enhance both growth and yield.

High turnover and selective Bin-Pd-NCs catalyst for nitro group non-hydrogen reductions in H2O under air conditions: A sustainable and recyclable route to aromatic amines

A green synthesis of anilines by the non-hydrogen reduction of nitro compounds is described. The reaction and post-treatment purification processes can produce high-purity target products without the use of organic solvents. The key to success lies in the synergistic action of two reaction mechanisms. The hydrogen transfer system is significantly accelerated by the presence of binaphthyl-palladium nanoclusters, which permits the catalyzed selective transfer hydrogenation under air conditions, providing a general preparation of aromatic amines in good-to-high yields with excellent chemoselectivities. Benefitting from the heterogeneous manner in water, successful recycling of the catalysts was further achieved with high reaction efficiency maintained. Meanwhile, the ICP analysis results show that the residual palladium content in the target product was below 5 ppm.

Edaravone for the Treatment of Motor Neurone Disease: A Critical Review of Approved and Alternative Formulations against a Proposed Quality Target Product Profile.

Edaravone is one of two main drugs for treating motor neurone disease (MND). This review proposes a specific quality target product profile (QTPP) for edaravone following an appraisal of the issues accounting for the poor clinical uptake of the approved IV and oral liquid edaravone formulations. This is followed by a review of the alternative oral formulations of edaravone described in the published patent and journal literature against the QTPP. A total of 14 texts published by six research groups on 18 novel oral formulations of edaravone for the treatment of MND have been reviewed. The alternative oral formulations included liquid and solid formulations developed with cyclodextrins, lipids, surfactants, co-surfactants, alkalising agents, tablet excipients, and co-solvents. Most were intended to deliver edaravone for drug absorption in the lower gastrointestinal tract (GIT); however, there were also four formulations targeting the oral mucosal absorption of edaravone to avoid first-pass metabolism. All the novel formulations improved the aqueous solubility, stability, and oral bioavailability (BA) of edaravone compared to an aqueous suspension of edaravone. A common limitation of the published formulations is the lack of MND-patient-centred data. Except for TW001, no other formulations have been trialled in MND patients. To meet the QTPP of an oral edaravone formulation for MND patients, it is recommended that a tablet of appropriate size and with acceptable taste and stability be designed for the effective sublingual or buccal absorption of edaravone. This tablet should be designed with input from the MND community.

Evolution of the Pd0/PdO phase change on Pd-MCM-41 catalyst for efficient production of furfural from the fast pyrolysis of cellulose

Furfural (C5H4O2) is a high-value platform chemical that is traditionally derived from the solvolysis of hemicellulose. However, its production from pyrolysis is far from satisfactory. In particular, the abundant cellulose within lignocellulosic biomass has yet to be successfully upgraded into furfural. Consequently, the overall yield of furfural from a lignocellulosic biomass is extremely low. Herein, we report a facile heterogeneous catalyst prepared from a simple impregnation of palladium (Pd) onto MCM-41 mesoporous silica. The catalyst demonstrated a remarkably high selectivity of ∼58.5% and yield of ∼32.5 wt% for furfural from the fast pyrolysis of wet cellulose. It was also confirmed to reach a selectivity of 65.4% and yield of 44.5 wt% for furfural from wet xylan, as well as a furfural yield of 23.9 wt% from wet sugarcane bagasse. All these values are superior to the literature reports. Through advanced characterisation including in-situ synchrotron high-temperature XRD and DRIFTS measurement, the loading of Pd in a tiny quantity of 1 mol% was confirmed to be sufficient in enhancing the surface hydrophilicity of the MCM-41 support, promoting the adsorption of reactants especially the formaldehyde group (HCHO), as well as the desorption of the target product furfural. In addition, Pd oxide (i.e., Pd2+O) was confirmed to be the catalytic active site. However, it was partly reduced into metallic Pd0 during the cellulose pyrolysis, due to the preferred reduction by adsorbed formaldehyde group and other reductants including H2 and CO in the vicinity of the PdO sites on the Pd-O-Si interface. Nevertheless, the catalyst was proven to retain the memory of its initial state after combustive regeneration in air, having oxidation state of Pd, particle size, and dispersion degree being reversed to its original construction. Accordingly, its activity remained stable upon cyclic testing. All these results demonstrate a high practical viability of this heterogenous catalyst for the valorisation of cellulose-rich biomass, an otherwise abundant crop waste across the world.