Single-Step Catalytic Conversion of Ethanol to n-Butene-Rich Olefins and 1,3-Butadiene Chemical Coproduct
This is the text version for the Single-Step Catalytic Conversion of Ethanol to n-Butene-Rich Olefins and 1,3-Butadiene Chemical Coproduct webinar.
>>Moderator: Hello everyone. And welcome to today's webinar, Single-Step Catalytic Conversion of Ethanol to n-Butene-Rich Olefins and 1,3-Butadiene Chemical Coproduct. The speakers today are Robert Dagle, Vanessa Dagle, and Zhenglong Li. Before we get started, I'd like to go over a few items so you know how to participate in today's event. You're listening in using your computer's speaker system by default. If you would prefer to join over the phone, just select telephone in the audio pane of your control panel and the dial-in information will be displayed.
You will have the opportunity to submit text questions to today's presenters by typing your questions into the question pane of the control panel. You may submit your questions at any time during the presentation. We will collect these and address them during the Q&A session at the end of today's presentation. If we don't have time for your questions today you can also feel free to email the presenters at their email address, which is in their slide. We will be recording today's webinar. You will receive a follow up email within a few weeks with a link to view the recording. Now, I will turn it over to Robert Dagle.
>>Robert Dagle: Okay. Great. Thank you. So we're going to talk about our single-step catalytic conversion of ethanol to n-butene-rich olefins and 1,3-butadiene chemical coproduct. Work that is being done at both Pacific Northwest National Laboratory and Oak Ridge National Laboratory. And we'll also touch on some of our other ethanol conversion work. There we go. Okay. So the three takeaways we'd like for you to get from this talk are shown here.
PNNL and Oak Ridge have developed catalysts and processes for the conversion of ethanol to fuels and coproducts. We present a flexible catalytic process for the single-step conversion of ethanol to butadiene or normal butenes using a mixed oxide catalyst. This is a new process that we've just recently been reporting on. This is what Vanessa and I and team have been working on at PNNL. We also present the catalytic processing for producing either C5+ hydrocarbon including BTX coproduct or C3+ olefins using zeolite catalysts. And this is research that Zhenglong, we at Oak Ridge, and team have been working on.
So I wanted to highlight. We are part of the Chemical Catalysis for Bioenergy Consortium or ChemCatBio. ChemCatBio is a national lab-led R&D consortium. Our mission is to accelerate commercialization of catalysts and processes related to the conversion of biomass and waste-derived fuels and chemicals. Our consortium leverages the expertise and capabilities across eight national laboratories. And a key benefit is that we have access to advanced characterization and computational tools and expertise that are leveraged across the national lab complex.
So here in this presentation, we are going to talk about our ethanol upgrading work. We think ethanol is an attractive feedstock. Ethanol is produced commercially from renewable biomass and waste sources. A lot of people think that ethanol prices will continue to come down. Everyone knows about the ethanol blend wall. the blend wall associated with gasoline blending. There's been advances in production efficiency and there's feedstock diversification. So people are interested in looking at producing value-added fuels and chemicals from ethanol.
So in this project at both PNNL and Oak Ridge we've been exploring multiple routes for ethanol upgrading shown here. PNNL co-developed an alcohol to jet process with LanzaTech who is currently commercializing the process shown at the top of the slide here, which produces an isoparaffin jet blendstock. It is produced through ethylene intermediate, which then requires a multistep oligomerization process. My colleagues at Oak Ridge developed a route to C5+ fuel-range hydrocarbons including BTX coproduct. This technology was licensed to Vertimass who is commercializing this technology.
More recently at both national labs, we've been looking to find more efficient routes to fuels, particularly distillate fuels and we've been looking at different coproduct possibilities. So Oak Ridge has worked to improve their zeolite catalysis to increase selectivity to the C5+ hydrocarbons. At PNNL we've looked at producing higher alcohols shown in the middle there via Guerbet catalysis and these higher alcohols can then be dehydrated and oligomerized to jet- and diesel-range hydrocarbons. And we've looked at producing isobutene directly from ethanol. The isobutene can be oligomerized into distillate-range hydrocarbons. This route enables less process steps than the incumbent distillate process. But it does have drawbacks particularly that we lose a significant amount of biomass direct carbon in the form of CO2. And I'll touch more on that in the next slide.
Very recently we've reported a promising new route where ethanol is converted directly into butadiene or normal butenes. Here no CO2 is produced. The route shown there at the bottom. We know how to selectively convert butenes to gasoline, jet, or diesel blendstocks. And so the key is getting to the butenes selectively and this is what we'll mostly talk about here. So I wanted to—but I did want to mention how we previously looked at conversion of ethanol to isobutene using a zinc zirconia type catalyst. This occurs over a single catalyst in a cascading sequence of reactions shown on the right. A big drawback is that it produces CO2 due to the ketonization required in the reaction network shown here in the middle. From ethanol one third of the biomass carbon—from the ethanol is lost to CO2.
So this really hurts the economics. So we moved away from this route for ethanol conversion. But I did want to point out that because of the reaction network, this catalyst system is quite versatile. It can upgrade a variety of feedstocks including alcohols, acids, aldehydes, ketones. So we think it has application elsewhere as we demonstrated for other applications. But for ethanol upgrading we're now focused on the catalyst that produces butadiene or normal butenes that doesn't produce CO2.
So why might butadiene itself be interesting? Butadiene is a commodity chemical that is used in a variety of products including synthetic rubbers. It's in tires. It's currently extracted from steam crackers as a byproduct but finding alternative sources of butadiene has received a lot of attention lately. With lighter feedstocks going to the steam crackers, from shale gas for example shown on the right people foresee supply shortages for things like butadiene and butenes and other naphtha-derived products. Butadiene is actually commercially produced for methanol before World War II. So the chemistry has been around for a while but really until quite recently the catalysts weren't very efficient for this reaction; yields to butadiene were quite low.
In this project, we've developed pretty good catalysts for butadiene production. So our prime objective in this project is really to produce distillate fuels and sometimes with coproducts. But here we wanted to share some preliminary economic projections for producing butadiene as a product using the catalysts we've developed. The red lines are the ranges of butadiene market prices. Over the past several years you can see that there's a pretty big variation. The yellow band shown here is what the butadiene selling price might be for our process given a wide range of ethanol feedstock prices from 85 cents to $2.70 a gallon. The yellow band—I'm sorry—the grey band range is what the butadiene price would be given a tighter ethanol feedstock price range, which approximates today's market prices.
So our primary takeaway here is that producing butadiene from ethanol could be cost-competitive with current butadiene prices given sufficiently low ethanol cost. And this is without RINs. So we think there might be some future opportunity here particularly if butadiene prices, market prices increase. And here we show butadiene as a case study. But we did the same sort of analysis for producing butanol and mixed normal butenes using our catalyst developed and we get a similar story. Given sufficienly low ethanol feedstock costs, the economics could be favorable for these types of commodity chemicals and without RINs. So now I'm going to turn it over to Vanessa who is going to talk about the butadiene butene catalysis.
>>Vanessa: Thank you. Historically for the single-step conversion of ethanol to butadiene, the butadiene yields have been low and high selectivity to butadiene of about 70 percent have been a (inaudible) slow conversion, typically lower than 40 percent. However, recently a silver zirconia silicone catalyst that was developed by the (inaudible) have shown some promise. And as shown in the table here and they were able to obtain high selectivity of butadiene of about 71 percent at relatively high conversion of 55 percent.
Following the preliminary work at PNNL we have developed our own silver zirconia silica formulation and we tested the catalyst under the same condition. To our surprise the PNNL catalyst was more active. We were able to obtain 89 percent of conversion and maintain high selectivity to butadiene of about 74 percent. So as you can see from the table, the butadiene yield is 1.5 times higher with the PNNL formation. So we decided to further investigate this catalyst.
So we prepared a series of silver zirconia silica catalysts with the same silver (inaudible), the same zirconia (inaudible), but different silica support. And as you can see from this table here, both conversion and butadiene selectivity changed greatly depending on the silica support. While some catalysts show little activity or no activity for butadiene prediction the catalyst that was synthesized from the SBA-16 support present high conversion of 99 percent and high selectivity to the butadiene of 71 percent. So this result shows that the choice of the silica support is key in effective catalyst design for butadiene prediction.
To verify the mechanism for the single-step conversion of ethanol to butadiene we conducted a standalone study over a wide range of conversions, which is shown on the figure on your right. You can see that while the selectivity to acetaldehyde decreases with increase of the conversion the selectivity to crotonaldehyde increases at first and then it decreases. And the selectivity to butadiene keeps increasing with increase of the conversion up to about 90 percent. The selectivity trend confirmed that both acetaldehyde and crotonaldehyde are intermediate involved in the formation of butadiene, which confirms the reaction measured involving aldol condensation followed by MPV reaction.
So to understand the role of each of the catalyst components silver, zirconia, and silica we synthesize different catalysts that are listed in the table here. And you can see that when we test silica alone the conversion is low and it leads mainly to the formation of acetaldehyde. Adding four percent of zirconia to the silica support helps the formation of undesired dehydration product, which are ethylene and diethyl ether, which is likely due to the fact that we add some acid sites with the zirconia and that's why the ethylene and diethyl ether are going up.
When instead of adding zirconia we add silver to the silica the conversion increases significantly. But the product is acetaldehyde just like for silica. So the silver boosts the conversion of ethanol to acetaldehyde. Finally when we add zirconia to the silver silica we can see there is not a significant impact on the conversion. It goes from 88 to 89 percent. But there is a drastic change in selectivity since when we add zirconia, the production of butadiene is facilitated and we make butadiene instead of acetaldehyde.
For the catalyst it's pretty complex since it concerns different acid sites. It contains some silver metal site and also some acid site. And both of them could impact the conversion. However we were not able to establish a relationship between the conversion and the total concentration of the acid site. Furthermore, when we add zirconia to the silver silica this does not impact the conversion. This suggested to us that silver could be responsible for the ethanol conversion. So for a series of silver zirconia silica catalyst with the (inaudible) but difference in catalyst support, we perceive the conversion as the function of the surface areas first and then as a function of the silver dispersion. Those are the two figures represented here. You can see that the conversion increases with the silver dispersion. So what does it mean? The higher is the surface area of the silica support, the higher is the silver dispersion, the higher is the quantity of silver particles capable of converting ethanol. So this is one of the reasons why the choice of the silica support is crucial because of the BET surface.
For the single-step conversion of ethanol to butadiene, many have reported that the acidity is crucial. So we have investigated the acidity using (inaudible) absorption (inaudible) followed by infrared spectroscopy. So the result obtained for a series of silver zirconia silica catalysts with different zirconia (inaudible) are presented here. The spectra were representative of (inaudible) for any of the catalysts we have made with this formulation. We do see dense characteristic of Lewis acid sites on the fresh catalysts but no (inaudible) characteristic of a Bronsted acid site have been detected for any of the catalysts. From this infrared experiment we quantified the acid site and we (inaudible) the butadiene selectivity as a function of the concentration of the acid site. So there's a figure on your bottom and it was presented here for two reasons. The blue diamond represents the same (inaudible), same zirconia, but different silica support. And the orange square represents catalyst with same (inaudible), same silica support but different zirconia.
So as you can see the butadiene selectivity decreases with the increase of the concentration of the acid site. So we need some acid site to allow the conversion of acetaldehyde to butadiene. But we don't need too many acid sites. There is an optimal quantity here that is required. So depending of the choice of the silica support the interaction between zirconia and silica changes, which affect the concentration of the acid site and the butadiene selectivity. This is a second reason why the choice of the silica support is crucial.
For this project we have been collaborating with CCPC. CCPC is the Consortium for Computational Physics and Chemistry. They looked at two models, a model with dispersed silver representing small silver particles. And a model with silver nanoparticles representative of larger silver particles. The DFT conversion suggested that the larger silver particles furthered the formation of ethylene. And the smaller silver particles are preferred to make butadiene. So from the (inaudible) we synthesized two catalysts, with same silver (inaudible) but different particle size. One catalyst with a particle size of about 1.9 nanometer and a second catalyst with an average particle size of 3.2 nanometer. So as you can see from the histogram higher butadiene production and lower ethylene formation was observed for the catalyst with the smaller silver particles. So here the experimental research validated the DFT calculation indicating that greater silver dispersion can inhibit the formation of the undesired dehydration product.
For the conversion of ethanol to butadiene we typically (inaudible) on the inert environment. We decided to investigate the effect of the environment on the catalytic performance. As you can see from the table here on the inert atmosphere of 99 percent conversion we produced butadiene with a selectivity of about 71 percent. When we switch from the inert environment to a reducing environment butadiene is no longer seen. Instead there is a significant amount of butene that is produced. This further shows that we can make butene from ethanol in one single step. And interestingly is the olefin double bond environment even under the reducing environment. So the important thing to remember from this slide is that we can produce butene-rich olefin directly from ethanol, which is a unique operation thereby representing a larger improvement compared to the state of the art where it goes to ethylene intermediate.
There are different pathways from which butene can be produced. They can be obtained via partial hydrogenation of butadiene. So on the mechanism here this is represented by the green arrows. It can also be potentially produced via butanol and butyraldehyde (inaudible). This is represented by the red arrows here. The space velocity profile of a wide range of conversion and selectivity shows that acetaldehyde and butadiene are the main intermediates. So butenes are mainly produced from butadiene partial hydrogenation for the green pathway. What this figure doesn't show you is that when we operate a slow conversion we see a smaller amount of butyraldehyde in the liquid phase.
To verify the formation of butyraldehyde we conducted some—one ex operando NMR. The figure on the very left presents the NMR spectra that was collected during the reaction in a slow conversion. From this characteristic of crotonaldehyde was seen at first. Looking at the peak at about 90 PM you can see that it decreases in intensity as direction progresses indicating that crotonaldehyde is being consumed. And the peak on the left of crotonaldehyde was identified at butyraldehyde. And this peak develops, with time, it increases and then it decreases, which confirms that at low conversion a portion of the butene is produced from butyraldehyde intermediate.
We also conducted some experiments where instead of using ethanol we used (inaudible) and to my biggest surprise here with (inaudible) we did not observe any peak characteristic of butyraldehyde. This means that the hydrogen that is needed to reduce crotonaldehyde to butyraldehyde does not come from H2. It comes from ethanol and it follows an MPV type prediction. So the bottom line from these studies that butenes are mainly produced from butadiene but at low conversion, a small portion is also produced from butyraldehyde.
We conducted a lifetime study, one of the (inaudible) inert atmosphere and under reducing atmosphere. Under reducing environment the conversion is pretty stable as you can see. It's represented by the blue circles here. When we operate under inert atmosphere the conversion decreases with time. But the activity can be recovered by a simple treatment under air. We've done total carbon analysis of the spin center and it has indicated that the center operating of the inert environment contents about twice as much carbon as compared to the one operated under reduced environment. And the characterization using normal spectroscopy and conducted by ACSC has indicated that the carbon deposits are in the form of carbon graphite. By the way for those who don't know ACSC, ACSC is the Advanced Catalyst Synthesis and Characterization project within ChemCatBio. Also note here that we've done—established measurement to determine the particle size of the silver (inaudible) and we do see a slight sintering interaction the silver particle size of about two nanometer and after (inaudible) it's about four nanometer, which could explain the initial drop of conversion that we see when we looked at it under reducing atmosphere.
So now let's look at the evolution of the product selectivity with time on stream, when we operate on the reducing environment. So the results are presented in the figure located on your right. The selectivity to the desired olefins represented by the orange triangles decreases with time on stream. And the butadiene product that was not observed at first during the first hours, gradually increases with time as you can see. However, by a simple regeneration treatment we were able to reduce the butadiene selectivity. So the regeneration treatment mitigates the butadiene formation.
So a few key points here that I would like to highlight. We have developed a flexible process for prediction of butadiene or butene-rich olefins from ethanol. This is a single-step process. When we operate under inert atmosphere butadiene is the main product. When we operate under a reducing atmosphere butene-rich olefins are produced. And with the best catalyst is how we've been able to obtain 70 percent selectivity to butadiene at 99 percent of conversion, (inaudible) conversion, and 85 percent selectivity to olefins at 94 percent (inaudible) conversion. And finally the catalyst lifetime study shows reversible deactivation. So now I'm going to hand it off to Zhenglong Li from Oak Ridge who is going to present the work conducted for the single-step conversion of ethanol over zeolite catalyst.
>>Zhenglong Li: All right. Thank you Vanessa. As was mentioned I'm Zhenglong from Oak Ridge National Lab. So going to talk to you about the zeolite catalysis and that's one of the interesting materials that we use for biomass conversion as we think it provides a very good support for anchor multiple different active sites. And also due to the (inaudible) we think we have the opportunity to tune the product selectivity. We have been working on three primary technologies on ethanol conversion.
And the first one is, take ethanol to make a C5+ hydrocarbons or metal modified Bronsted acid zeolite. And with the target to making gasoline- or jet-range hydrocarbons and also could produce BTX as the product. This technology, as Rob mentioned earlier, has been licensed through Vertimass. And right now Vertimass is commercializing this technology with the support from DOE Bioenergy Technologies Office. And also ChemCatBio also offers an advanced characterization to accelerate commercial catalyst development through the directive from the assisting program.
The other two works is mainly focused on ethanol to C3+ olefins. And the top one is over Bronsted acid zeolite. And we're producing C3+ olefins together with aromatics. And the bottom one is Lewis acid zeolite, very high selective production of C3+ mixed olefins from ethanol. And for the remaining of the webinar I'm going to give a very brief overview of these two technologies on converting ethanol to C3+ olefins and hopefully to give you a little bit of flavor of the work we're doing here at Oak Ridge. And if you have a more detailed question regarding these technologies please see the bottom contact information there. We'll be happy to follow up with more detailed questions there.
And for ethanol-to-jet, the C3+ olefins are very important intermediates as you can see from the top flow chart there. As Rob mentioned earlier, so their approach there you can use a two-step approach to convert ethanol to mixed olefins, first by doing dehydration of ethanol to make ethylene and then do oligomerization to make a butene-rich olefin there. And so our work we're primarily interested in is one-step conversion, bypassing the ethylene production step because that's an endothermic reaction. We also hope to reduce one unit operation.
And so we're primarily interested in two pathways. The bottom pathway as shown in the gold line here basically takes ethanol over the Bronsted acid zeolite to making C3+ olefin together with aromatics. Also the top pathway there goes through a cascade reaction to convert ethanol to acetaldehyde and also continue to convert that to mixed olefins. And the primary goal is really try to increase the carbon efficiency by mainly inhibiting or avoid CO2 formation from this reaction here. And over Bronsted acid zeolite as you can see the last flow chart here, it is showing the proposed major reaction steps if you take ethanol to making olefins and also aromatics. As you can see, ethylene is one of the very important intermediates there. Once you form ethylene that can go through oligomerization to make other light olefins like butene, propane, which can also further go through oligomerization to making other longer chain olefins and also oligomerization to make aromatics. Also from the right figure you can see at a higher reaction temperature beside the C3+ olefin production there, typically we're also producing paraffins as a side product there. So the project here really tries to minimize the paraffin formation.
And for that ethanol conversion step there the downstream ethylene conversion is really one of the most important steps and which has been an interest for a lot of groups. And here if you look at the top table, I'm showing you one example that this group they are looking at ethylene conversion on different zeolite with different pore size. And we can clearly see that the medium pore zeolite like H-ZSM-5 and also small pore H-SSZ-13, both of them give higher ethylene conversion and also higher selectivity for propene and butene, which are very interesting materials to look at.
Coke formation is typically a challenge for this kind of hydrocarbon conversion especially for small pore zeolites. So our initial motivation is to really try to look at different types of material to address the coke formation and hopefully to further improve the C3+ olefin from ethanol conversion. And while the material that we're interested in is MFI type zeolite is a 2D pillared MFI zeolite. As you can see from the bottom left figure this type of zeolite has other mesopore structure there. And also it's well known for the reduced diffusion lens, which has potential to significantly reduce the coke formation. And also this type of a pillar zeolite also shown a very different acid site distribution compared to conventional MFI as you can see from the right table there. The pillared MFI tends to have a much higher external surface acid site. And we're interested to see how this acid site distribution impacts on the product distribution.
And here I'm showing you the comparison between these two types of zeolites at same reaction conditions and with similar silicon ratio. From the top figure you can clearly tell there's a big difference between the product distribution there. And the bottom figure might be easier to look at. And so basically on the pillared MFI we're able to significantly increase the C3, C5 light olefins and also minimize the light paraffin and also aromatic formation. This might be a combination of both the reduced diffusion lens and also the acid site distribution.
I just want to focus on how the reduced diffusion lens affecting the product selectivity we try to control the ethylene conversion at similar range. As you can see from this table here, similar ethylene conversion and pillared MFI were producing significantly more propane and butenes, which is very interesting. And by indicating the reduced diffusion lens has a positive impact on the light olefin production. We've also shown that the pillared MFI can significantly reduce the coke formation compared to the conventional ZSM-5. And all of this suggesting the pillared MFI is an interesting catalyst for ethanol conversion to C3+ olefins. And we're interested to further learn more about this reaction mechanism. Especially for ethanol conversion we're producing water there. So the water role in this (inaudible) here is very important. And also through this understanding we hope to further reduce ethylene and also paraffin formation.
The other pathway that we're interested in is one-step conversion of ethanol to C3+ olefin over Lewis acid zeolite, hopefully to develop a catalyst or system there that can give a very high selectivity of the targeted olefin there. As Vanessa mentioned earlier for this type of chemistry it requires different types of active sites there. I'm also showing you here, if you want to do the first-step dehydrogenation and we can use metal like silver as Vanessa just mentioned there. And also we can choose copper and zinc and there might be other sites we can use. And then once you have the acetaldehyde there we need to do the carbon-carbon bond formation and here we're using the aldol condensation chemistry either developing Lewis acid sites or basic sites, try to do the condensation to making a longer chain intermediate there. And we need additional sites to do the dehydration and also transfer hydrogenation to make the target olefin there. So you can tell this is a very complicated system and so choosing the right metal and also balance the site are really critical and we hope to achieve this through developing Lewis acid zeolite to do this.
We have worked on different types of Lewis acid zeolites in the last two years by varying the metal centers of the Lewis acid site and also different zeolite topology and also looking at introducing different metal combinations there and try to maximize the total olefin production. Here I'm showing you one example that we developed for this one-step conversion and which is copper zinc hafnium-BEA Lewis acid zeolite. As you can see from this table on this catalyst we're able to selectively make close to 70 percent C3+ olefin selectivity. And also among this butene is the dominating fraction there. The total olefin is also pretty high and still with significant amount of ethylene formation there. And we're continuing working on understanding active sites on this catalyst and try to minimize the ethylene formation. And also on a couple of other catalyst systems there we have made significant improvement there to advancing the C3+ olefin selectivity, which is much higher than also than this number I showed here.
38:09 But more importantly I want to put this in a bigger picture how this one-step conversion can play into the big picture for ethanol conversion to jet fuel. Once you produce the mixed olefin and we can keep that to do oligomerization, hydrotreating to make the jet-range hydrocarbons. If you compare this with the conventional two-step ethanol to ethylene, also higher C3+ olefin two-step approach there. And we think by bypassing this ethanol dehydration step we're able to remove one-step operation and also changing from endothermic dehydration reaction to slightly exothermic reaction there. Right now we're able to minimize the ethylene production below 10 percent and so that we can avoid the downstream ethylene separation step, which might be an energy-intensive process.
And by doing all of this we think there's opportunity we can further reduce the CAPEX and OPEX for this technology. We also started to demonstrate mixed olefin oligomerization. And you can see the bottom picture there, which showing one of the examples, one of the samples that we produced in the lab by oligomerization of this mixed olefin there. And also after hydrotreating. And for the left, for the right bar chart there I'm showing you the product distribution after oligomerization. The left part is the carbon number distribution. As you can clearly see the yellow bar there is the jet-range hydrocarbon. Right now it's about very close to 70 percent. And we're also producing about 25 percent gasoline-range hydrocarbon, which is shown in the green bar there.
And for the right side, for the liquid we're collecting from the oligomerization step is primarily isoparaffinic-type hydrocarbons, which is one of the dominating fractions in the petroleum-derived jet hydrocarbons. And this is just one example of the oligomerization experiment to show here and we hope—we still have a lot of flexibility to tune that to achieve a high product flexibility. And overall for the whole process here and based on this number we think we have a pretty high overall carbon efficiency from ethanol to final jet. And also there are about 84 percent of the theoretical yield are recovered in the final liquid field.
With that, I'd like to conclude this webinar. Hopefully both offers we have shown you these labs have developed different catalysts and processes for converting ethanol to fuels and coproducts. So at PNNL they have shown a flexible catalytic process for single-step conversion of ethanol to either butadiene or normal butene. And for this reaction and a different environment there, they can selectively make butadiene or butene. On both the silver zirconia silica or this Lewis acid zeolite we're able to demonstrate one-step selective conversion from ethanol to high olefin.
And in the next step we're going to further improve C3+ olefin selectivity and also look into further enhance the catalyst stability if we see any durability challenge there and also further evaluate with real fermentation broths and also demonstrate conversion to distillate-range hydrocarbons to meet different field perspectives there. With that, finally we want to acknowledge funding from DOE Bioenergy Technologies Office. Also Chemical Catalysis for Bioenergy Consortium. And also all the participants who contribute a lot for this work here. And thank you very much for listening to this webinar and we hope to answer the questions you might have there.
>>Moderator: Hello. Thank you so much Zhenglong. We're now going to begin answering the questions submitted during today's presentation. As a reminder you can still submit questions through the questions pane in your attendee control panel. All right. So our first question is, do these processes require 100 percent ethanol feedstock or can 95 percent ethanol be used?
>>Vanessa Dagle: Yes, we can use 95 percent of ethanol. We've done some tests with ethanol and water and we can operate with water; 95 percent of ethanol in water will be fine.
>>Moderator: All right. We're only going to be able to take two questions today just due to time limitations but I'm going to read the second one now. Did you assess the effect of impurities in ethanol such as water on catalyst performance? This is important and azeotropic ethanol is used as a raw material for the process.
>>Vanessa Dagle: Yes. We have done some tests with ethanol and water. We've done some tests with 95 percent ethanol in water and some tests with 35 percent ethanol in water to represent the composition before and after the (inaudible). When we operate with water we do see a drop of conversion but it's not that bad. It does not seem to impact the deactivation. The deactivation rather seems to be faster when we operate with water.
>>Moderator: Okay. Thank you. For additional questions, again please email the presenters directly at their email address listed on their slide. Thank you everyone today for attending today's webinar. You will receive a follow up email within the next couple weeks with a link to view a recording of today's webinar. Thank you for joining us today and have a great rest of your day.
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