2015 Impact Factor: 1.043
Enzyme-instructed self-assembly (EISA) offers a facile approach to explore the supramolecular assemblies of small molecules in cellular milieu for a variety of biomedical applications. One of the commonly used enzymes is phosphatase, but the study of the substrates of phosphatases mainly focuses on the phosphotyrosine containing peptides. In this work, we examine the EISA of phosphoserine containing small peptides for the first time by designing and synthesizing a series of precursors containing only phosphoserine or both phosphoserine and phosphotyrosine. Conjugating a phosphoserine to the C-terminal of a well-established self-assembling peptide backbone, (naphthalene-2-ly)-acetyl-diphenylalanine (NapFF), affords a novel hydrogelation precursor for EISA. The incorporation of phosphotyrosine, another substrate of phosphatase, into the resulting precursor, provides one more enzymatic trigger on a single molecule, and meanwhile increases the precursors’ propensity to aggregate after being fully dephosphorylated. Exchanging the positions of phosphorylated serine and tyrosine in the peptide backbone provides insights on how the specific molecular structures influence self-assembling behaviors of small peptides and the subsequent cellular responses. Moreover, the utilization of D-amino acids largely enhances the biostability of the peptides, thus providing a unique soft material for potential biomedical applications.
Ferritin, a major iron storage protein with a hollow interior cavity, has been reported recently to play many important roles in biomedical and bioengineering applications. Owing to the unique architecture and surface properties, ferritin nanoparticles offer favorable characteristics and can be either genetically or chemically modified to impart functionalities to their surfaces, and therapeutics or probes can be encapsulated in their interiors by controlled and reversible assembly/disassembly. There has been an outburst of interest regarding the employment of functional ferritin nanoparticles in nanomedicine. This review will highlight the recent advances in ferritin nanoparticles for drug delivery, bioassay, and molecular imaging with a particular focus on their biomedical applications.
Membrane distillation crystallization (MDC) is a promising hybrid separation process that has been applied to seawater desalination, brine treatment and wastewater recovery. In recent years, great progress has been made in MDC technologies including the promotion of nucleation and better control of crystallization and crystal size distribution. These advances are useful for the accurate control of the degree of supersaturation and for the control of the nucleation kinetic processes. This review focuses on the development of MDC process models and on crystallization control strategies. In addition, the most important innovative applications of MDC in the last five years in crystal engineering and pharmaceutical manufacturing are summarized.
Hexagonal CePO4 nanorods were prepared by a precipitation method and hexagonal CePO4 nanowires were prepared by hydrothermal synthesis at 150 °C. Rh(NO3)3 was then used as a precursor for the impregnation of Rh2O3 onto these CePO4 materials. The Rh2O3 supported on the CePO4 nanowires was much more active for the catalytic decomposition of N2O than the Rh2O3 supported on CePO4 nanorods. The stability of both catalysts as a function of time on stream was studied and the influence of the co-feed (CO2, O2, H2O or O2/H2O) on the N2O decomposition was also investigated. The samples were characterized by N2 adsorption-desorption, inductively coupled plasma optical emission spectroscopy, X-ray diffraction, transmission electron microscopy, X-ray photoelectron microscopy, hydrogen temperature-programmed reduction, oxygen temperature-programmed desorption, and CO2 temperature-programmed desorption in order to correlate the physicochemical and catalytic properties.
An anticancer drug delivery system consisting of DNA nanoparticles synthesized by rolling circle amplification (RCA) was developed for prostate cancer membrane antigen (PSMA) targeted cancer therapy. The template of RCA was a DNA oligodeoxynucleotide coded with PSMA-targeted aptamer, drug-loading domain, primer binding site and pH-sensitive spacer. Anticancer drug doxorubicin, as the model drug, was loaded into the drug-loading domain (multiple GC-pair sequences) of the DNA nanoparticles by intercalation. Due to the integrated pH-sensitive spacers in the nanoparticles, in an acidic environment, the cumulative release of doxorubicin was far more than the cumulative release of the drug in the normal physiological environment. In cell uptake experiments, treated with doxorubicin loaded DNA nanoparticles, PSMA-positive C4-2 cells could take up more doxorubicin than PSMA-null PC-3 cells. The prepared DNA nanoparticles showed the potential as drug delivery system for PSMA targeting prostate cancer therapy.
Small interfering RNA (siRNA) therapeutics hold great promise to treat a variety of diseases, as long as they can be delivered safely and effectively into cells. Dendrimers are appealing vectors for siRNA delivery by virtue of their well-defined molecular architecture and multivalent cooperativity. However, the clinical translation of RNA therapeutics mediated by dendrimer delivery is hampered by the lack of dendrimers that are of high quality to meet good manufacturing practice standard. In this context, we have developed small amphiphilic dendrimers that self-assemble into supramolecular structures, which mimic high-generation dendrimers synthesized with covalent construction, yet are easy to produce in large amount and superior quality. Indeed, the concept of supramolecular dendrimers has proved to be very promising, and has opened up a new avenue for dendrimer-mediated siRNA delivery. A series of self-assembling supramolecular dendrimers have consequently been established, some of them out-performing the currently available nonviral vectors in delivering siRNA to various cell types in vitro and in vivo, including human primary cells and stem cells. This short review presents a brief introduction to RNAi therapeutics, the obstacles to their delivery and the advantages of dendrimer delivery vectors as well as our bio-inspired structurally flexible dendrimers for siRNA delivery. We then highlight our efforts in creating self-assembling amphiphilic dendrimers to construct supramolecular dendrimer nanosystems for effective siRNA delivery as well as the related structural alterations to enhance delivery efficiency. The advent of self-assembling supramolecular dendrimer nanovectors holds great promise and heralds a new era of dendrimer-mediated delivery of RNA therapeutics in biomedical applications.
Platelets dynamically participate in various physiological processes, including wound repair, bacterial clearance, immune response, and tumor metastasis. Recreating the specific biological features of platelets by mimicking the structure of the platelet or translocating the platelet membrane to synthetic particles holds great promise in disease treatment. This review highlights recent advancements made in the platelet-mimicking strategies. The future opportunities and translational challenges are also discussed.
In the transformation of methanol to gasoline (MTG), the selectivity to gasoline and the aromatic content in the produced gasoline are important factors. The catalytic activities of steam-treated and non-steam-treated nano-scale H-ZSM-5 (NHZ5) catalysts impregnated with Ag(I), Zn(II) or P(V) have been investigated in a continuous flow fixed bed reactor. The NH3-TPD results showed that after impregnation, the Ag/NHZ5, Zn/NHZ5 and P/NHZ5 catalysts contained comparatively more strong, medium-strong and weak acid sites, respectively. Treatment with steam decreased the number of acid sites in all the catalysts, but the pore volumes in the catalysts were larger which improved carbon deposition resistance resulting in prolonged lifetimes. After 6 h of MTG reaction, the selectivity to gasoline for the steam-treated catalysts, AgH2O/NHZ5, ZnH2O/NHZ5 and PH2O/NHZ5 were 70.5, 68.4 and 68.7 wt-%, respectively, whereas their respective aromatic contents in the produced gasoline were 61.9, 55.4 and 39.0 wt-%. Thus PH2O/NHZ5 is the most promising catalyst for MTG applications which can meet the China IV gasoline standard that the amount of aromatics in gasoline should be less than 48 wt-%.
Despite limited successes in clinical development, therapeutic cancer vaccines have experienced resurgence in recent years due to an enhanced emphasis upon co-mitigating factors underlying immune response. Specifically, reversing the immune-suppressive effects of the tumor microenvironment, mediated by a variety of cellular and molecular signaling mechanisms, has become fundamental toward enhancing therapeutic efficacy. Therein, our lab has implemented various nano-vaccines based on the lipid-coated calcium phosphate platform for combined immunotherapy, in which antigenic, epitope-associated peptides as well as immune-suppression inhibitors can be co-delivered, often functioning through the same formulation. In probing the mechanism of action of such systems in vitro andin vivo, an improved effect synergy can be elucidated, inspiring future preclinical efforts and hope for clinical success.
A mild in-situdeposition method was used to fabricate Mn-based catalysts on a UiO-66 carrier for the selective catalytic reduction of NO by NH3 (NH3-SCR). The catalyst with 8.5 wt-% MnOx loading had the highest catalytic activity for NH3-SCR with a wide temperature window (100–290 °C) for 90% NO conversion. Characterization of the prepared MnOx/UiO-66 catalysts showed that the catalysts had the crystal structure and porosity of the UiO-66 carrier and that the manganese particles were well-distributed on the surface of the catalyst. X-ray photoelectron spectroscopy analysis showed that there are strong interactions between the MnOx and the Zr oxide secondary building units of the UiO-66 which has a positive effect on the catalytic activity. The 8.5 wt-% MnOx catalyst maintained excellent activity during a 24-h stability test and exhibited good resistance to SO2 poisoning.
CO oxidation has been investigated on three CuO/CeO2 catalysts prepared by impregnation, co-precipitation and mechanical mixing. The origin of active sites was explored by the multiple techniques. The catalyst prepared by impregnation has more highly dispersed CuO and stronger interactions between CuO and CeO2 to promote the reduction of CuO to Cu+ species at the Cu-Ce interface, leading to its highest catalytic activity. For the catalyst prepared by co-precipitation, solid solution structures observed in Raman spectra suppress the formation of the Cu-Ce interface, where the adsorbed CO will react with active lattice oxygen to form CO2, and thus it displays a lower catalytic performance. No Cu-Ce interface exists in the catalyst prepared by the mechanical mixing method due to the separate phases of CuO and CeO2, resulting in its lowest activity among the three catalysts.
The effects of Na+, Mg2+, Al3+ and Fe3+ ion concentrations on the crystal morphology of calcium sulfate hemihydrate whiskers formed via a hydrothermal method have been studied. In the presence of Al3+ concentrations higher than 1×10−3 mol/L the whiskers were significantly shorter and thicker and the presence of Mg2+ and Fe3+ resulted in shorter whiskers. The presence of Na+ did not affect the morphology of the whiskers. Through elemental analysis, it was determined that Mg2+ and Al3+ were selectively adsorbed on the surfaces of the crystals, whereas Fe3+ underwent a hydrolysis reaction to form a brown precipitate which decreased the ion concentration in the solution. These results indicate that in raw materials used for the industrial preparation of calcium sulfate whiskers, Al3+ and Fe3+ should be removed and the Mg2+ concentration should be less than 8 × 10−3 mol/L in order to obtain pure whiskers with high aspect ratios.
Toluene methylation with methanol offers an alternative method to produce p-xylene by gathering methyl group directly from C1 chemical sources. It supplies a “molecular engineering” process to realize directional conversion of toluene/methanol molecules by selective catalysis in complicated methylation system. In this review, we introduce the synthesis method of p-xylene, the development history of methylation catalysts and reaction mechanism, and the effect of reaction condition in para-selective technical process. If constructing p-xylene as the single target product, the major challenge to develop para-selective toluene methylation is to improve the p-xylene selectivity without, or as little as possible, losing the fraction of methanol for methylation. To reach higher yield of p-xylene and more methanol usage in methylation, zeolite catalyst design should consider improving mass transfer and afterwards covering external acid sites by surface modification to get short “micro-tunnels” with shape selectivity. A solid understanding of mass transfer will benefit realizing the aim of converting more methanol feedstock into para-methyl group.
Bleached bamboo kraft pulp was pretreated by 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO)-mediated oxidation using a TEMPO/NaBr/NaClO system at pH= 10 in water to facilitate mechanical disintegration into TEMPO-oxidized cellulose nanofibrils (TO-CNs). A series of TO-CNs with different carboxylate contents were obtained by varying amounts of added NaClO. An increase in carboxylate contents results in aqueous TO-CN dispersions with higher yield, zeta potential values, and optical transparency. When carboxylate groups are introduced, the DPv value of the TO-CNs remarkably decreases and then levels off. And the presence of hemicellulose in the pulp is favorable to TEMPO oxidization. After the oxidization, the native cellulose I crystalline structure and crystal size of bamboo pulp are almost maintained. TEM micrographs revealed that the degree of nanofibrillation is directly proportional to the carboxylate contents. With increasing carboxylate contents, the free-standing TO-CN films becomes more transparent and mechanically stronger. The oxygen permeability of PLA films drastically decreases from 355 for neat PLA to 8.4 mL·m−2·d−1 after coating a thin layer of TO-CN with a carboxylate content of 1.8 mmol·g−1. Therefore, inexpensive and abundant bamboo pulp would be a promising starting material to isolate cellulose nanfibrils for oxygen-barrier applications.
The application of gene delivery materials has been mainly focused on mammalian cells while rarely extended to plant engineering. Cationic polymers and lipids have been widely utilized to efficiently deliver DNA and siRNA into mammalian cells. However, their application in plant cells is limited due to the different membrane structures and the presence of plant cell walls. In this study, we developed the cationic, α-helical polypeptide that can effectively deliver DNA into both isolated Arabidopsis thaliana protoplasts and intact leaves. The PPABLG was able to condense DNA to form nanocomplexes, and they exhibited significantly improved transfection efficiencies compared with commercial transfection reagent Lipofectamine 2000 and classical cell penetrating peptides such as poly(L-lysine), HIV-TAT, arginine9, and poly(L-arginine). This study therefore widens the utilities of helical polypeptide as a unique category of gene delivery materials, and may find their promising applications toward plant gene delivery.
Flower-like intercalated MoS2 nanomaterials have been successfully synthesized via a microemulsion-mediated hydrothermal (MMH) method, and characterized by X-ray diffraction, Raman spectroscopy, element analysis, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, and Fourier transform infrared spectroscopy in detail. Their catalytic performance for anthracene hydrogenation was evaluated using a slurry-bed batch reactor with an initial hydrogen pressure of 80 bar at 350 °C for 4 h. The intercalated MoS2 nanoflowers synthesized from Na2MoO4 (MoS2-S) and H2MoO4 (MoS2-A) as molybdenum precursors have diameters of about 150 and 50 nm, respectively. MoS2 nanosheets on MoS2-S and MoS2-A possess stacking layer numbers of 5–10 and 2–5, and slab lengths of about 15 and 10 nm, respectively. The interlayer distances of MoS2-S and MoS2-A are both enlarged from 0.62 nm to about 0.95 nm due to the intercalation of NH4+ and surfactant molecules. The MoS2 nanoflowers have high catalytic activities for anthracene hydrogenation. The selectivity for octahydroanthracene, a deeply hydrogenated product, over MoS2-A is 89.8%, which is 31.0 times higher than that over commercial bulk MoS2. Fully hydrogenated product (perhydroanthracene) was also detected over MoS2 nanoflowers with a selectivity of 3.7%. The enhanced hydrogenation activities of MoS2 nanoflowers can be ascribed to the high exposure of catalytic active sites, resulting from the smaller particle size, fewer stacking layer, shorter slab length and enlarged interlayer distance of MoS2 nanoflowers compared with commercial bulk MoS2. In addition, a possible growth mechanism of MoS2 nanoflowers synthesized via the MMH method was proposed.
Carbon deposition and sintering of active components such as nano particles are great challenges for Ni-based catalysts for CO methanation to generate synthetic natural gas from syngas. Facing the challenges, bimetallic catalysts with different Fe content derived from layered double hydroxide containing Ni, Fe, Mg, Al elements were prepared by co-precipitation method. Nanoparticles of Ni-Fe alloy were supported on mixed oxides of aluminium and magnesium after calcination and reduction. The catalysts were characterized by Brunner-Emmett-Teller (BET), X-ray diffraction, hydrogen temperature programmed reduction, inductively coupled plasma, X-ray photoelectron spectroscopy, transmission electron microscopy and thermogravimetric techniques, and their catalytic activity for CO methanation was investigated. The results show that the Ni-Fe alloy catalysts exhibit better catalytic performance than monometallic catalysts except for the Ni4Fe-red catalyst. The Ni2Fe-red catalyst shows the highest CO conversion (100% at 260–350 °C), as well as the highest CH4 selectivity (over 95% at 280–350 °C), owing to the formation of Ni-Fe alloy. In stability test, the Ni2Fe-red catalyst exhibits great improvement in both anti-sintering and resistance to carbon formation compared with the Ni0Fe-red catalyst. The strong interaction between Ni and Fe element in alloy and surface distribution of Fe element not only inhibits the sintering of nanoparticles but restrains the formation of Ni clusters.
In this study, we developed a three-stage catalyst-adsorbent reactor for the catalytic hydrolysis of CF4. Each stage is composed of a catalyst bed followed by an adsorbent bed using Ca(OH)2 to remove HF. The three stages are connected in series to enhance the hydrolysis of CF4 and eliminate a scrubber to dissolve HF in water at the same time. With a 10 wt-% Ce/Al2O3 catalyst prepared by the incipient wetness method using boehmite and a granular calcium hydroxide as an adsorbent, the CF4 conversion in our proposed reactor was 7%–23% higher than that in a conventional single-bed catalytic reactor in the temperature range of 923–1023 K. In addition, experimental and numerical simulation (Aspen HYSYS®) results showed a reasonable trend of increased CF4 conversion with the adsorbent added and these results can be used as a useful design guideline for our newly proposed multistage reactor system.
A comparative analysis of perovskite structured cathode materials, La0.65Sr0.35MnO3 (LSM), La0.8Sr0.2CoO3 (LSC), La0.6Sr0.4FeO3 (LSF) and La0.6Sr0.4Co0.2Fe0.8O3 (LSCF), was performed for a ceramic-carbonate nanocomposite fuel cell using composite electrolyte consisting of Gd0.1Ce0.9O1.95 (GDC) and a eutectic mixture of Na2CO3 and Li2CO3. The compatibility of these nanocomposite electrode powder materials was investigated under air, CO2 and air/CO2 atmospheres at 550 °C. Microscopy measurements together with energy dispersive X-ray spectroscopy (EDS) elementary analysis revealed few spots with higher counts of manganese relative to lanthanum and strontium under pure CO2 atmosphere. Furthermore, electrochemical impedance (EIS) analysis showed that LSC had the lowest resistance to oxygen reduction reaction (ORR) (14.12 Ω·cm2) followed by LSF (15.23 Ω·cm2), LSCF (19.38 Ω·cm2) and LSM (>300 Ω·cm2). In addition, low frequency EIS measurements (down to 50 µHz) revealed two additional semi-circles at frequencies around 1 Hz. These semicircles can yield additional information about electrochemical reactions in the device. Finally, a fuel cell was fabricated using GDC/NLC nanocomposite electrolyte and its composite with NiO and LSCF as anode and cathode, respectively. The cell produced an excellent power density of 1.06 W/cm2 at 550 °C under fuel cell conditions.
We have successfully prepared a series of Pd-Ni/TiO2 catalysts by a one-step impregnation-reduction method. Among these catalysts with different compositions of Ni and Pd, the one with the Ni:Pd ratio of 2.95 showed the best activity. Small monodispersed Pd-Ni bimetallic nanoparticles were loaded on the surface of titanium oxide nanopowder as confirmed with TEM and EDS mapping. The XPS analysis demonstrated that Pd exists as 31% Pd(II) species and 69% Pd(0) species and all nickel is Ni(II). The prepared Pd-Ni/TiO2 exhibited enhanced catalytic activity compared to an equal amount of Pd/TiO2 for Suzuki-Miyaura reactions together with excellent applicability and reusability.
This study described a template-free method for the synthesis of hierarchically macro-mesoporous Mn-TiO2 catalysts. The promoting effect of Mn doping and the hierarchically macro-mesoporous architecture on TiO2 based catalysts was also investigated for the selective reduction of NO with NH3. The results show that the catalytic performance of TiO2 based catalysts was improved greatly after Mn doping. Meanwhile, the Mn-TiO2 catalyst with the hierarchically macro-mesoporous architecture has a better catalytic activity than that without such an architecture.
Hydroformylation has been widely used in industry to manufacture high value-added aldehydes and alcohols, and is considered as the largest homogenously catalyzed process in industry. However, this process often suffers from complicated operation and the difficulty in catalyst recycling. It is highly desirable to develop a heterogeneous catalyst that enables the catalyst recovery without sacrificing the activity and selectivity. There are two strategies to afford such a catalyst for the hydrofromylation: immobilized catalysts on solid support and porous organic ligand (POL)-supported catalysts. In the latter, high concentration of phosphine ligands in the catalyst framework is favorable for the high dispersion of rhodium species and the formation of Rh-P multiple bonds, which endow the catalysts with high activity and stability respectively. Besides, the high linear regioselectivity could be achieved through the copolymerization of vinyl functionalized bidentate ligand (vinyl biphephos) and monodentate ligand (3vPPh3) into the catalyst framework. The newly-emerging POL-supported catalysts have great perspectives in the industrial hydroformylation.
The patient receives a pharmaceutical product, not a drug. The pharmaceutical products are formulated with a drug, an active ingredient to produce the maximum therapeutic effect after oral absorption. Therefore, it is the product we must optimize for the patients. In order to assure the safety and efficacy of pharmaceutical products, we need an in vivo predictive tool for oral product performance in patients. Currently, we are a surprisingly long way from accomplishing that objective. If the 20th century was the ‘age of the drug’, i.e., the ‘magic bullet’, the 21st century must become the ‘age of the guided missile’, i.e., the delivery system, including the form of the active pharmaceutical ingredient (API) (‘drug’). The physical form of the drug and the delivery system must be optimized to maximize the therapeutic benefits of pharmaceutical products for humans. Oral immediate release (IR) dosage forms cannot be optimal for all drugs or likely even any drugs (APIs). Still, the formulation of pharmaceutical products has to be optimized for patients. But how do we optimize oral delivery of drugs? It is usually through ‘trial and error’, in humans! We need a better way to optimize the oral dosage forms. We have suggested to select different dissolution methodologies for this optimization based on BCS Subclasses. In this article, we present the predicted in vivo drug dissolution profile of ketoconazole as a model drug from our laboratory utilizing a gastrointestinal simulator (GIS), which is an adaptation of the ASD system. GIS consists of three chambers representing stomach, duodenum, and jejunum, to create the human gastrointestinal tract-like environment and enable the control the gastric emptying rate. This dissolution system allows the monitoring of the drug dissolution phenomena and the observation of the supersaturation and the precipitation of pharmaceutical products, which is useful information to predict in vivo dissolution of pharmaceutical products. This system can provide the actual input needed to accurately predict the input into the systemic circulation required by many of the absorption prediction packages available today.
In-line hydro-treatment of bio-oil vapor from fast pyrolysis of lignocellulosic biomass (hydro-pyrolysis of biomass) is studied as a method of upgrading the liquefied bio-oil for a possible precursor to green fuels. The nobel metal (Pt) and non-noble metal catalysts (Mo2C and WC) were compared at 500 °C and atmospheric pressure which are same as the reaction conditions for fast pyrolysis of biomass. Results indicated that under the pyrolysis conditions, the major components, such as acids and carbonyls, of the fast pyrolysis bio-oil can be completely and partially hydrogenated to form hydrocarbons, an ideal fossil fuel blend, in the hydro-treated bio-oil. The carbide catalysts perform equally well as the Pt catalyst regarding to the aliphatic and aromatic hydrocarbon formation (ca. 60%), showing the feasibility of using the cheap non-noble catalysts for hydro-pyrolysis of biomass.
There is currently a growing interest in the realisation and optimization of hybrid plasma/catalyst systems for a multitude of applications, ranging from nanotechnology to environmental chemistry. In spite of this interest, there is, however, a lack in fundamental understanding of the underlying processes in such systems. While a lot of experimental research is already being carried out to gain this understanding, only recently the first simulations have appeared in the literature. In this contribution, an overview is presented on atomic scale simulations of plasma catalytic processes as carried out in our group. In particular, this contribution focusses on plasma-assisted catalyzed carbon nanostructure growth, and plasma catalysis for greenhouse gas conversion. Attention is paid to what can routinely be done, and where challenges persist.
A significant portion of the world’s population does not have access to safe drinking water. This problem is most acute in remote, resource-constrained rural settings in developing countries. Water filtration using activated carbon is one of the important steps in treating contaminated water. Lignocellulosic biomass is generally available in abundance in such locations, such as the African rain forests. Our work is focused on developing a simple method to synthesize activated biochar from locally available materials. The preparation of activated biochar with diammonium hydrogenphosphate (DAP) as the activating agent is explored under N2 flow and air. The study, carried out with cellulose as a model biomass, provides some insight into the interaction between DAP and biomass, as well as the char forming mechanism. Various characterization techniques such as N2 physisorption, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy and Raman spectroscopy are utilized to compare the properties between biochar formed under nitrogen and partial oxidative conditions. At a temperature of 450 °C, the loading of DAP over cellulose is systematically varied, and its effect on activation is examined. The activated biochar samples are predominantly microporous in the range of concentrations studied. The interaction of DAP with cellulose is investigated and the nature of bonding of the heteroatoms to the carbonaceous matrix is elucidated. The results indicate that the quality of biochar prepared under partial oxidation condition is comparable to that of biochar prepared under nitrogen, leading to the possibility of an activated biochar production scheme on a small scale in resource-constrained settings.
This paper overviews the development of the anthraquinone auto-oxidation (AO) process for the production of hydrogen peroxide in China and abroad. The characteristics and differences between the fixed-bed and fluidized-bed reactors for the AO process are presented. The detailed comparison indicates that the production of hydrogen peroxide with the fluidized-bed reactor has many advantages, such as lower operation cost and catalyst consumption, less anthraquinone degradation, higher catalyst utilization efficiency, and higher hydrogenation efficiency. The key characters of the production technology of hydrogen peroxide based on the fluidized-bed reactor developed by the Research Institute of Petroleum Processing, Sinopec are also disclosed. It is apparent that substituting the fluidized-bed reactor for the fixed-bed reactor is a major direction of breakthrough for the production technology of hydrogen peroxide in China.
Detection of oxygen and carbon dioxide is important in the field of chemical and biosensors for atmosphere and biosystem monitoring and fermentation processes. The present study reports on the preparation of zeolite films doped with iron nanoparticles for detection of CO2 and O2 in gas phase. Pure nanosized LTL type zeolite with monomodal particle size distribution loaded with iron (Fe-LTL) was prepared under hydrothermal condition from colloidal precursor suspensions. The zeolite was loaded with iron to different levels by ion exchange. The Fe-LTL suspensions were used for preparation of thin films on silicon wafers via spin coating method. The reduction of the iron in the zeolite films was carried out under H2 flow (50% H2 in Ar) at 300 °C. The presence of iron nanoparticles is proved by in situ ultra-violet-visible spectroscopy. The properties of the films including surface roughness, thickness, porosity, and mechanical stability were studied. In addition, the loading and distribution of iron in the zeolite films were investigated. The Fe-LTL zeolite films were used to detect O2 and CO2 in a concentration dependent mode, followed by IR spectroscopy. The changes in the IR bands at 855 and 642 cm−1 (Fe–O–H and Fe–O bending vibrations) and at 2363 and 2333 cm−1 (CO2 asymmetric stretching) corresponding to the presence of O2 and CO2, respectively, were evaluated. The response to O2 and CO2 was instant, which was attributed to great accessibility of the iron in the nanosized zeolite crystals. The saturation of the Fe-LTL films with CO2 and O2 at each concentration was reached within less than a minute. The Fe-LTL films detected both oxygen and carbon dioxide in contrast, to the pure LTL zeolite film.
The maximizing iso-paraffins (MIP) developed by RIPP has improved gasoline quality to meet the demand of motor gasoline specification. A concept that two different reaction zones include cracking zone and conversion zone is proposed as the fundamental of MIP by research on fluid catalytic cracking (FCC) reaction chemistry. Based on the concept, the MIP process is featured by applying a novel sequential two-zone riser in conjunction with proprietary catalyst and engineering technique. The developed MIP process can not only improve gasoline yield or gasoline plus propylene yields but also produce gasoline with a higher content of iso-paraffins and a lower content of sulfur. A minimum octane number loss is achieved when MIP gasoline is treated by downstream desulfurization technology (RSDS/S Zorb). The combination of MIP and RSDS/S Zorb processes creates a very competitive route, which is different from the technical route used by other developed countries, to upgrade the quality of motor gasoline with the lowest economic costs in China. In just one decade, the processing capacity of MIP units has accounted for about 60% of the domestic total processing capacity of FCC units. The MIP process is gradually becoming a new generation of FCC technology.