•The importance of furfural and hydroxymethylfurfural increased in the past years.•Heterogeneous acid-catalysts were widely reported for furan-derivative production.•This review focuses on the yields ...of different microporous and mesoporous materials.
The production of value-added chemicals from renewable sources, such as biomass-derived carbohydrates, is an emerging field. The amount of publications in the field of pentose and hexose conversion to furfural and hydroxymethylfurfural has considerably increased in the recent years. Most of these studies focus on using heterogeneous acid-catalysts to selectively convert these carbohydrates into the desired products at optimized yields. This review aims to summarize the most significant studies reporting the conversion of C5 and C6 carbohydrates using different structured materials. The final goal is to provide with a general overview of the broad spectrum of heterogeneous catalysts studies and the correlation between their physicochemical properties, with a special attention on the pore structure, and the catalytic activity under different reaction conditions, such as solvents or temperature. In the case of furfural, as it is already a commercial product, a short overview of the manufacturing process and the current improvements will also be given. The future studies reporting the carbohydrate dehydration reactions to furfural and HMF could take advantage of this study to select the physicochemical properties of the catalysts required to achieve their specific goals.
N2-stripping for furfural production from biomass.
•The use of N2-stripping shows higher yields than steam-stripping.•A one step hydrolysis–dehydration achieves higher furfural yields.•The modeling ...data using N2-stripping show higher furfural concentration.•The annual utility costs are considerably reduced compared to steam-stripping.
Among the furan-based compounds, furfural (FUR) shows interesting properties as building-block or industrial solvent. It is produced from pentosan-rich biomass via xylose cyclodehydration. The current FUR production makes use of homogeneous catalysts and excessive amounts of steam. The development of greener furfural production and separation techniques implies the use of heterogeneous catalysts and innovative separation processes. This work deals with the conversion of corncobs as xylose source to be dehydrated to furfural. The results reveal differences between the use of direct corncob hydrolysis and dehydration to furfural and the prehydrolysis and dehydration procedures. Moreover, this work focuses on an economical analysis of the main process parameters during N2-stripping and its economical comparison to the current steam-stripping process. The results show a considerable reduction of the annual utility costs due to use of recyclable nitrogen and the reduction of the furfural purification stages.
Nickel catalysts supported on Al
2
O
3
, Al
2
O
3
-CeO
2
, Al
2
O
3
-La
2
O
3
, and Al
2
O
3
-CeO
2
-La
2
O
3
were synthesized
via
the sol-gel method in acidic solution. The influence of the chemical ...composition and textural properties of the catalysts on oxidative steam reforming of methane was studied. Methane, oxygen, nitrogen and steam were fed into a fixed bed reactor and tested under atmospheric pressure at 550 °C, with O/C ratio = 0.3, S/C ratio = 1.0, and WHSV = 170.8 h
−1
. During 6 h of reaction, methane conversion and hydrogen selectivity were determined. Although lanthanide oxides are known to have excellent features, the addition of ceria or lanthana did not improve the catalytic performance of the Ni/Al
2
O
3
system. Nevertheless the addition of both dopants was needed to end up with a stable catalyst. Characterization results revealed a low crystallite size (40 Å), a high fraction of accessible Ni
0
species (73.6%), migration of nickel and ceria from the bulk to the surface during activity tests, and a very low amount of coke deposited (4.7 mg C per g catalyst) on the Ni/Al
2
O
3
-CeO
2
-La
2
O
3
catalyst that resulted in high catalytic activity.
Nickel supported on Al
2
O
3
-CeO
2
-La
2
O
3
provided excellent catalytic features and high coking resistance in oxidative steam reforming of methane.
The one-pot production of a relevant chemical such as 1,5-pentanediol (1,5-PDO) from sustainable sources (furfural) is a key reaction to compete with existing fossil sources. This work provides new ...evidence on the influence of the starting reagent, the features of layered double hydrotalcite (LDH)-derived catalysts in the form of mixed metal oxides (MMO) and of reaction conditions on the productivity of 1,5-PDO under batch conditions. Unlike reported studies, these results suggest the direct pathway through furfuryl alcohol intermediates, allowing the one-pot production from furfural at lower temperature than analogous systems. Productivity is maximized when Co
2+
species partially substitute Mg
2+
species in parent LDH, yielding promising pentanediol yields under mild reaction conditions. MMOs containing Co
2+
sites show marked differences compared to analogous bivalent metals, which is here attributed to the position in which reaction intermediates such as furfuryl alcohol are adsorbed onto surface specie. This is consistent with characterized surface species by XRD, temperature programmed reduction under H
2
, and chemisorption experiments using CO or CO
2
as probe molecules, indicative of a proper balance between metal and basic sites onto MMOs. The reported data aim to provide new reaction evidence to contribute into the search of sustainable 1,5-PDO sources.
Graphical Abstract
Objective To predict the real-world (RW) cost-effectiveness of carfilzomib in combination with lenalidomide and dexamethasone (KRd) versus lenalidomide and dexamethasone (Rd) in relapsed multiple ...myeloma (MM) patients after one to three prior therapies. Methods A partitioned survival model that included three health states (progression-free, progressed disease and death) was built. Progression-free survival (PFS), overall survival (OS) and time to discontinuation (TTD) data for the Rd arm were derived using the Registry of Monoclonal Gammopathies in the Czech Republic; the relative treatment effects of KRd versus Rd were estimated from the phase 3, randomised, ASPIRE trial, and were used to predict PFS, OS and TTD for KRd. The model was developed from the payer perspective and included drug costs, administration costs, monitoring costs, palliative care costs and adverse-event related costs collected from Czech sources. Results The base case incremental cost effectiveness ratio for KRd compared with Rd was ϵ73,156 per quality-adjusted life year (QALY) gained. Patients on KRd incurred costs of ϵ117,534 over their lifetime compared with ϵ53,165 for patients on Rd. The QALYs gained were 2.63 and 1.75 for patients on KRd and Rd, respectively. Conclusions Combining the strengths of randomised controlled trials and observational databases in cost-eifectiveness models can generate policy-relevant results to allow well-informed decision-making. The current model showed that KRd is likely to be cost-eifective versus Rd in the RW and, therefore, the reimbursement of KRd represents an efficient allocation of resources within the healthcare system.
The low-temperature dehydration of bioethanol-to-ethylene is of great interest to reduce energy consumption and achieve high product purities in the biorefinery and olefin industry. Thermokinetic ...constraints, however, lead to low ethylene selectivity at low temperature. In this work, we integrate a new approach that combines a hierarchical acid H-form ZSM-5 (HZSM-5) with systematic catalytic testing to study how the physicochemical modification of the surface and intermediate catalytic species affect the ethanol-to-ethylene route at 225 °C. Four HZSM-5 zeolites were treated with OH species under basic conditions (OH
−
) or solely with H
2
O. Kinetic evidence coupled to
27
Al-nuclear magnetic resonance, NH
3
-temperature-programmed desorption and N
2
adsorption, as well as density-functional theory calculations, correlate ethylene selectivity with the appearance of new extra-framework Al(
v
) and Al(
vi
) species, acting as Lewis acid-sites. The adopted approach allows us to experimentally unveil the cooperative effect between Brønsted- and Lewis-acid sites that seem to play a key role in ethylene formation from ethanol at low-temperature
via
(i) a primary route
via
ethanol dimerization on neighboring Brønsted-acid sites to diethylether, which subsequently cracked on Lewis-acid sites to ethylene; (ii) a secondary route
via
the direct ethanol dehydration on Brønsted-acid sites. Theoretical calculations support the proposed catalytic cycle. These new insights shed light on the mechanism of ethanol-to-ethylene at low temperature, and on how the precise control over the strength of acid-sites and their population in HZSM-5 affects catalysis. This work progresses towards more active and stable catalysts, advancing into more mature low-temperature technologies for the dehydration of bioethanol into sustainable ethylene.
We highlight the role of OH-treated weakly acidic ZSM-5 in the ethanol-to-ethylene at low temperature. Ethylene forms via (i) primary dimer from ethanol on Brønsted sites, followed by diethyl ether cracking on Lewis sites, and (ii) secondary cleavage of C-OH in ethanol over Brønsted sites.
► Nitrogen stripping combined with Amberlyst 70 allows high furfural yield. ► Product selectivity in the condensate stream is almost 100%. ► Less cooling energy requirements than using steam and easy ...recyclability of nitrogen. ► Water–furfural phase separation occurs at high initial xylose loadings. ► Modeling results are valuable for further continuous process designs.
The aim of this work deals with the development of new approaches to the production of furfural from xylose. It combines relatively cheap heterogeneous catalysts (Amberlyst 70) with simultaneous furfural stripping using nitrogen under semi-batch conditions. Nitrogen, compared to steam, does not dilute the vapor phase stream when condensed. This system allowed stripping 65% of the furfural converted from xylose and almost 100% of selectivity in the condensate. Moreover, high initial xylose loadings led to the formation of two water–furfural phases, which could reduce further purification costs. Constant liquid–vapor equilibrium along stripping could be maintained for different xylose loadings. The modeling of the experimental data was carried out in order to obtain a liquid–vapor mass-transfer coefficient. This value could be used for future studies under steady-state continuous conditions in similar reaction-systems.
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